# MGLSymbolStyleLayer

    @interface MGLSymbolStyleLayer : MGLVectorStyleLayer

An `MGLSymbolStyleLayer` is a style layer that renders icon and text labels at points or along lines on the map.

Use a symbol style layer to configure the visual appearance of feature labels. These features can come from vector tiles loaded by an `MGLVectorTileSource` object, or they can be `MGLShape` or `MGLFeature` instances in an `MGLShapeSource` or `MGLComputedShapeSource` object.

You can access an existing symbol style layer using the `-[MGLStyle layerWithIdentifier:]` method if you know its identifier; otherwise, find it using the `MGLStyle.layers` property. You can also create a new symbol style layer and add it to the style using a method such as `-[MGLStyle addLayer:]`.

#### Related examples

See the Dynamically style interactive points and Use images to cluster point data examples learn how to style data on your map using this layer.

### Example

    let layer = MGLSymbolStyleLayer(identifier: "coffeeshops", source: pois)
    layer.sourceLayerIdentifier = "pois"
    layer.iconImageName = NSExpression(forConstantValue: "coffee")
    layer.iconScale = NSExpression(forConstantValue: 0.5)
    layer.text = NSExpression(forKeyPath: "name")
    layer.textTranslation = NSExpression(forConstantValue: NSValue(cgVector: CGVector(dx: 10, dy: 0)))
    layer.textJustification = NSExpression(forConstantValue: "left")
    layer.textAnchor = NSExpression(forConstantValue: "left")
    layer.predicate = NSPredicate(format: "%K == %@", "venue-type", "coffee")
    mapView.style?.addLayer(layer)

- `-initWithIdentifier:source:`

  Returns a symbol style layer initialized with an identifier and source.

  After initializing and configuring the style layer, add it to a map view’s style using the `-[MGLStyle addLayer:]` or `-[MGLStyle insertLayer:belowLayer:]` method.

  #### Declaration

  Objective-C

      - (nonnull instancetype)initWithIdentifier:(nonnull NSString *)identifier
                                          source:(nonnull MGLSource *)source;

  Swift

      init(identifier: String, source: MGLSource)

  #### Parameters

  `identifier` | A string that uniquely identifies the source in the style to which it is added.
  `source` | The source from which to obtain the data to style. If the source has not yet been added to the current style, the behavior is undefined.

  #### Return Value

  An initialized foreground style layer.

  View Source on GitHub

### Accessing the Layout Attributes

- `iconAllowsOverlap`

  If true, the icon will be visible even if it collides with other previously drawn symbols.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-allow-overlap` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconAllowsOverlap;

  Swift

      var iconAllowsOverlap: NSExpression! { get set }

  View Source on GitHub
- `iconAnchor`

  Part of the icon placed closest to the anchor.

  The default value of this property is an expression that evaluates to `center`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLIconAnchor` values
  - Any of the following constant string values:
    - `center`: The center of the icon is placed closest to the anchor.
    - `left`: The left side of the icon is placed closest to the anchor.
    - `right`: The right side of the icon is placed closest to the anchor.
    - `top`: The top of the icon is placed closest to the anchor.
    - `bottom`: The bottom of the icon is placed closest to the anchor.
    - `top-left`: The top left corner of the icon is placed closest to the anchor.
    - `top-right`: The top right corner of the icon is placed closest to the anchor.
    - `bottom-left`: The bottom left corner of the icon is placed closest to the anchor.
    - `bottom-right`: The bottom right corner of the icon is placed closest to the anchor.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconAnchor;

  Swift

      var iconAnchor: NSExpression! { get set }

  View Source on GitHub
- `iconIgnoresPlacement`

  If true, other symbols can be visible even if they collide with the icon.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-ignore-placement` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconIgnoresPlacement;

  Swift

      var iconIgnoresPlacement: NSExpression! { get set }

  View Source on GitHub
- `iconImageName`

  Name of a style image to use for drawing an image background.

  Use the `+[MGLStyle setImage:forName:]` method to associate an image with a name that you can set this property to.

  Within a constant string value, a feature attribute name enclosed in curly braces (e.g., `{token}`) is replaced with the value of the named attribute. Tokens inside non-constant expressions are ignored; instead, use `mgl_join:` and key path expressions.

  This attribute corresponds to the `icon-image` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant string values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Related examples

  See the Use images to cluster point data example to learn how to dynamically set your icons with an expression.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconImageName;

  Swift

      var iconImageName: NSExpression! { get set }

  View Source on GitHub
- `iconOffset`

  Offset distance of icon from its anchor.

  The default value of this property is an expression that evaluates to an `NSValue` object containing a `CGVector` struct set to 0 rightward and 0 downward. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `CGVector` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconOffset;

  Swift

      var iconOffset: NSExpression! { get set }

  View Source on GitHub
- `iconOptional`

  If true, text will display without their corresponding icons when the icon collides with other symbols and the text does not.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`, and `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (getter=isIconOptional, assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconOptional;

  Swift

      var iconOptional: NSExpression! { get set }

  View Source on GitHub
- `iconPadding`

  Size of the additional area around the icon bounding box used for detecting symbol collisions.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `2`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconPadding;

  Swift

      var iconPadding: NSExpression! { get set }

  View Source on GitHub
- `iconPitchAlignment`

  Orientation of icon when map is pitched.

  The default value of this property is an expression that evaluates to `auto`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLIconPitchAlignment` values
  - Any of the following constant string values:
    - `map`: The icon is aligned to the plane of the map.
    - `viewport`: The icon is aligned to the plane of the viewport.
    - `auto`: Automatically matches the value of `icon-rotation-alignment`.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconPitchAlignment;

  Swift

      var iconPitchAlignment: NSExpression! { get set }

  View Source on GitHub
- `iconRotation`

  Rotates the icon clockwise.

  This property is measured in degrees.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-rotate` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconRotation;

  Swift

      var iconRotation: NSExpression! { get set }

  View Source on GitHub
- `iconRotationAlignment`

  In combination with `symbolPlacement`, determines the rotation behavior of icons.

  The default value of this property is an expression that evaluates to `auto`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLIconRotationAlignment` values
  - Any of the following constant string values:
    - `map`: When `symbol-placement` is set to `point`, aligns icons east-west. When `symbol-placement` is set to `line` or `line-center`, aligns icon x-axes with the line.
    - `viewport`: Produces icons whose x-axes are aligned with the x-axis of the viewport, regardless of the value of `symbol-placement`.
    - `auto`: When `symbol-placement` is set to `point`, this is equivalent to `viewport`. When `symbol-placement` is set to `line` or `line-center`, this is equivalent to `map`.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconRotationAlignment;

  Swift

      var iconRotationAlignment: NSExpression! { get set }

  View Source on GitHub
- `iconScale`

  Scales the original size of the icon by the provided factor. The new point size of the image will be the original point size multiplied by `iconScale`. 1 is the original size; 3 triples the size of the image.

  This property is measured in factor of the original icon sizes.

  The default value of this property is an expression that evaluates to the float `1`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-size` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconScale;

  Swift

      var iconScale: NSExpression! { get set }

  View Source on GitHub
- `iconTextFit`

  Scales the icon to fit around the associated text.

  The default value of this property is an expression that evaluates to `none`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`, and `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLIconTextFit` values
  - Any of the following constant string values:
    - `none`: The icon is displayed at its intrinsic aspect ratio.
    - `width`: The icon is scaled in the x-dimension to fit the width of the text.
    - `height`: The icon is scaled in the y-dimension to fit the height of the text.
    - `both`: The icon is scaled in both x- and y-dimensions.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconTextFit;

  Swift

      var iconTextFit: NSExpression! { get set }

  View Source on GitHub
- `iconTextFitPadding`

  Size of the additional area added to dimensions determined by `iconTextFit`.

  This property is measured in points.

  The default value of this property is an expression that evaluates to an `NSValue` object containing `UIEdgeInsetsZero`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`, and `text` is non-`nil`, and `iconTextFit` is set to an expression that evaluates to `MGLIconTextFitBoth`, `MGLIconTextFitWidth`, or `MGLIconTextFitHeight`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `UIEdgeInsets` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconTextFitPadding;

  Swift

      var iconTextFitPadding: NSExpression! { get set }

  View Source on GitHub
- `keepsIconUpright`

  If true, the icon may be flipped to prevent it from being rendered upside-down.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`, and `iconRotationAlignment` is set to an expression that evaluates to `map`, and `symbolPlacement` is set to an expression that evaluates to either `MGLSymbolPlacementLine` or `MGLSymbolPlacementLineCenter`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-keep-upright` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *keepsIconUpright;

  Swift

      var keepsIconUpright: NSExpression! { get set }

  View Source on GitHub
- `keepsTextUpright`

  If true, the text may be flipped vertically to prevent it from being rendered upside-down.

  The default value of this property is an expression that evaluates to `YES`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`, and `textRotationAlignment` is set to an expression that evaluates to `map`, and `symbolPlacement` is set to an expression that evaluates to either `MGLSymbolPlacementLine` or `MGLSymbolPlacementLineCenter`. Otherwise, it is ignored.

  This attribute corresponds to the `text-keep-upright` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *keepsTextUpright;

  Swift

      var keepsTextUpright: NSExpression! { get set }

  View Source on GitHub
- `maximumTextAngle`

  Maximum angle change between adjacent characters.

  This property is measured in degrees.

  The default value of this property is an expression that evaluates to the float `45`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`, and `symbolPlacement` is set to an expression that evaluates to either `MGLSymbolPlacementLine` or `MGLSymbolPlacementLineCenter`. Otherwise, it is ignored.

  This attribute corresponds to the `text-max-angle` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *maximumTextAngle;

  Swift

      var maximumTextAngle: NSExpression! { get set }

  View Source on GitHub
- `maximumTextWidth`

  The maximum line width for text wrapping.

  This property is measured in ems.

  The default value of this property is an expression that evaluates to the float `10`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-max-width` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *maximumTextWidth;

  Swift

      var maximumTextWidth: NSExpression! { get set }

  View Source on GitHub
- `symbolAvoidsEdges`

  If true, the symbols will not cross tile edges to avoid mutual collisions. Recommended in layers that don’t have enough padding in the vector tile to prevent collisions, or if it is a point symbol layer placed after a line symbol layer.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This attribute corresponds to the `symbol-avoid-edges` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *symbolAvoidsEdges;

  Swift

      var symbolAvoidsEdges: NSExpression! { get set }

  View Source on GitHub
- `symbolPlacement`

  Label placement relative to its geometry.

  The default value of this property is an expression that evaluates to `point`. Set this property to `nil` to reset it to the default value.

  You can set this property to an expression containing any of the following:

  - Constant `MGLSymbolPlacement` values
  - Any of the following constant string values:
    - `point`: The label is placed at the point where the geometry is located.
    - `line`: The label is placed along the line of the geometry. Can only be used on `LineString` and `Polygon` geometries.
    - `line-center`: The label is placed at the center of the line of the geometry. Can only be used on `LineString` and `Polygon` geometries. Note that a single feature in a vector tile may contain multiple line geometries.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *symbolPlacement;

  Swift

      var symbolPlacement: NSExpression! { get set }

  View Source on GitHub
- `symbolSpacing`

  Distance between two symbol anchors.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `250`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `symbolPlacement` is set to an expression that evaluates to `line`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 1
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *symbolSpacing;

  Swift

      var symbolSpacing: NSExpression! { get set }

  View Source on GitHub
- `symbolZOrder`

  Controls the order in which overlapping symbols in the same layer are rendered

  The default value of this property is an expression that evaluates to `viewport-y`. Set this property to `nil` to reset it to the default value.

  You can set this property to an expression containing any of the following:

  - Constant `MGLSymbolZOrder` values
  - Any of the following constant string values:
    - `viewport-y`: Specify this z order if symbols’ appearance relies on lower features overlapping higher features. For example, symbols with a pin-like appearance would require this z order.
    - `source`: Specify this z order if the order in which features appear in the source is significant.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *symbolZOrder;

  Swift

      var symbolZOrder: NSExpression! { get set }

  View Source on GitHub
- `text`

  Value to use for a text label.

  Within a constant string value, a feature attribute name enclosed in curly braces (e.g., `{token}`) is replaced with the value of the named attribute. Tokens inside non-constant expressions are ignored; instead, use `mgl_join:` and key path expressions.

  The default value of this property is an expression that evaluates to the empty string. Set this property to `nil` to reset it to the default value.

  This attribute corresponds to the `text-field` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant string values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Related examples

  See the Cluster point data and Use images to cluster point data to learn how to use an expression to set this attribute to the number of markers within a cluster.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable) NSExpression *text;

  Swift

      var text: NSExpression! { get set }

  View Source on GitHub
- `textAllowsOverlap`

  If true, the text will be visible even if it collides with other previously drawn symbols.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-allow-overlap` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textAllowsOverlap;

  Swift

      var textAllowsOverlap: NSExpression! { get set }

  View Source on GitHub
- `textAnchor`

  Part of the text placed closest to the anchor.

  The default value of this property is an expression that evaluates to `center`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextAnchor` values
  - Any of the following constant string values:
    - `center`: The center of the text is placed closest to the anchor.
    - `left`: The left side of the text is placed closest to the anchor.
    - `right`: The right side of the text is placed closest to the anchor.
    - `top`: The top of the text is placed closest to the anchor.
    - `bottom`: The bottom of the text is placed closest to the anchor.
    - `top-left`: The top left corner of the text is placed closest to the anchor.
    - `top-right`: The top right corner of the text is placed closest to the anchor.
    - `bottom-left`: The bottom left corner of the text is placed closest to the anchor.
    - `bottom-right`: The bottom right corner of the text is placed closest to the anchor.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textAnchor;

  Swift

      var textAnchor: NSExpression! { get set }

  View Source on GitHub
- `textFontNames`

  An array of font face names used to display the text.

  Each font name must be included in the `{fontstack}` portion of the JSON stylesheet’s `glyphs` property. You can register a custom font when designing the style in Mapbox Studio. Fonts installed on the system are not used.

  The first font named in the array is applied to the text. For each character in the text, if the first font lacks a glyph for the character, the next font is applied as a fallback, and so on.

  The default value of this property is an expression that evaluates to the array `Open Sans Regular`, `Arial Unicode MS Regular`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-font` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant array values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textFontNames;

  Swift

      var textFontNames: NSExpression! { get set }

  View Source on GitHub
- `textFontSize`

  Font size.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `16`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-size` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textFontSize;

  Swift

      var textFontSize: NSExpression! { get set }

  View Source on GitHub
- `textIgnoresPlacement`

  If true, other symbols can be visible even if they collide with the text.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-ignore-placement` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textIgnoresPlacement;

  Swift

      var textIgnoresPlacement: NSExpression! { get set }

  View Source on GitHub
- `textJustification`

  Text justification options.

  The default value of this property is an expression that evaluates to `center`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-justify` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextJustification` values
  - Any of the following constant string values:
    - `left`: The text is aligned to the left.
    - `center`: The text is centered.
    - `right`: The text is aligned to the right.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textJustification;

  Swift

      var textJustification: NSExpression! { get set }

  View Source on GitHub
- `textLetterSpacing`

  Text tracking amount.

  This property is measured in ems.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textLetterSpacing;

  Swift

      var textLetterSpacing: NSExpression! { get set }

  View Source on GitHub
- `textLineHeight`

  Text leading value for multi-line text.

  This property is measured in ems.

  The default value of this property is an expression that evaluates to the float `1.2`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textLineHeight;

  Swift

      var textLineHeight: NSExpression! { get set }

  View Source on GitHub
- `textOffset`

  Offset distance of text from its anchor.

  This property is measured in ems.

  The default value of this property is an expression that evaluates to an `NSValue` object containing a `CGVector` struct set to 0 ems rightward and 0 ems downward. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `CGVector` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textOffset;

  Swift

      var textOffset: NSExpression! { get set }

  View Source on GitHub
- `textOptional`

  If true, icons will display without their corresponding text when the text collides with other symbols and the icon does not.

  The default value of this property is an expression that evaluates to `NO`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`, and `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant Boolean values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (getter=isTextOptional, assign, readwrite, nonatomic, null_resettable)
          NSExpression *textOptional;

  Swift

      var textOptional: NSExpression! { get set }

  View Source on GitHub
- `textPadding`

  Size of the additional area around the text bounding box used for detecting symbol collisions.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `2`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textPadding;

  Swift

      var textPadding: NSExpression! { get set }

  View Source on GitHub
- `textPitchAlignment`

  Orientation of text when map is pitched.

  The default value of this property is an expression that evaluates to `auto`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextPitchAlignment` values
  - Any of the following constant string values:
    - `map`: The text is aligned to the plane of the map.
    - `viewport`: The text is aligned to the plane of the viewport.
    - `auto`: Automatically matches the value of `text-rotation-alignment`.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textPitchAlignment;

  Swift

      var textPitchAlignment: NSExpression! { get set }

  View Source on GitHub
- `textRotation`

  Rotates the text clockwise.

  This property is measured in degrees.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-rotate` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant numeric values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textRotation;

  Swift

      var textRotation: NSExpression! { get set }

  View Source on GitHub
- `textRotationAlignment`

  In combination with `symbolPlacement`, determines the rotation behavior of the individual glyphs forming the text.

  The default value of this property is an expression that evaluates to `auto`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextRotationAlignment` values
  - Any of the following constant string values:
    - `map`: When `symbol-placement` is set to `point`, aligns text east-west. When `symbol-placement` is set to `line` or `line-center`, aligns text x-axes with the line.
    - `viewport`: Produces glyphs whose x-axes are aligned with the x-axis of the viewport, regardless of the value of `symbol-placement`.
    - `auto`: When `symbol-placement` is set to `point`, this is equivalent to `viewport`. When `symbol-placement` is set to `line` or `line-center`, this is equivalent to `map`.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textRotationAlignment;

  Swift

      var textRotationAlignment: NSExpression! { get set }

  View Source on GitHub
- `textTransform`

  Specifies how to capitalize text.

  The default value of this property is an expression that evaluates to `none`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextTransform` values
  - Any of the following constant string values:
    - `none`: The text is not altered.
    - `uppercase`: Forces all letters to be displayed in uppercase.
    - `lowercase`: Forces all letters to be displayed in lowercase.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textTransform;

  Swift

      var textTransform: NSExpression! { get set }

  View Source on GitHub

### Accessing the Paint Attributes

- `iconColor`

  The tint color to apply to the icon. The `iconImageName` property must be set to a template image.

  The default value of this property is an expression that evaluates to `UIColor.blackColor`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `UIColor` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconColor;

  Swift

      var iconColor: NSExpression! { get set }

  View Source on GitHub
- `iconColorTransition`

  The transition affecting any changes to this layer’s `iconColor` property.

  This property corresponds to the `icon-color-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconColorTransition;

  Swift

      var iconColorTransition: MGLTransition { get set }

  View Source on GitHub
- `iconHaloBlur`

  Fade out the halo towards the outside.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconHaloBlur;

  Swift

      var iconHaloBlur: NSExpression! { get set }

  View Source on GitHub
- `iconHaloBlurTransition`

  The transition affecting any changes to this layer’s `iconHaloBlur` property.

  This property corresponds to the `icon-halo-blur-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconHaloBlurTransition;

  Swift

      var iconHaloBlurTransition: MGLTransition { get set }

  View Source on GitHub
- `iconHaloColor`

  The color of the icon’s halo. The `iconImageName` property must be set to a template image.

  The default value of this property is an expression that evaluates to `UIColor.clearColor`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `UIColor` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconHaloColor;

  Swift

      var iconHaloColor: NSExpression! { get set }

  View Source on GitHub
- `iconHaloColorTransition`

  The transition affecting any changes to this layer’s `iconHaloColor` property.

  This property corresponds to the `icon-halo-color-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconHaloColorTransition;

  Swift

      var iconHaloColorTransition: MGLTransition { get set }

  View Source on GitHub
- `iconHaloWidth`

  Distance of halo to the icon outline.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconHaloWidth;

  Swift

      var iconHaloWidth: NSExpression! { get set }

  View Source on GitHub
- `iconHaloWidthTransition`

  The transition affecting any changes to this layer’s `iconHaloWidth` property.

  This property corresponds to the `icon-halo-width-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconHaloWidthTransition;

  Swift

      var iconHaloWidthTransition: MGLTransition { get set }

  View Source on GitHub
- `iconOpacity`

  The opacity at which the icon will be drawn.

  The default value of this property is an expression that evaluates to the float `1`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values between 0 and 1 inclusive
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconOpacity;

  Swift

      var iconOpacity: NSExpression! { get set }

  View Source on GitHub
- `iconOpacityTransition`

  The transition affecting any changes to this layer’s `iconOpacity` property.

  This property corresponds to the `icon-opacity-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconOpacityTransition;

  Swift

      var iconOpacityTransition: MGLTransition { get set }

  View Source on GitHub
- `iconTranslation`

  Distance that the icon’s anchor is moved from its original placement.

  This property is measured in points.

  The default value of this property is an expression that evaluates to an `NSValue` object containing a `CGVector` struct set to 0 points rightward and 0 points downward. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-translate` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant `CGVector` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconTranslation;

  Swift

      var iconTranslation: NSExpression! { get set }

  View Source on GitHub
- `iconTranslationTransition`

  The transition affecting any changes to this layer’s `iconTranslation` property.

  This property corresponds to the `icon-translate-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition iconTranslationTransition;

  Swift

      var iconTranslationTransition: MGLTransition { get set }

  View Source on GitHub
- `iconTranslationAnchor`

  Controls the frame of reference for `iconTranslation`.

  The default value of this property is an expression that evaluates to `map`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `iconImageName` is non-`nil`, and `iconTranslation` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `icon-translate-anchor` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant `MGLIconTranslationAnchor` values
  - Any of the following constant string values:
    - `map`: Icons are translated relative to the map.
    - `viewport`: Icons are translated relative to the viewport.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *iconTranslationAnchor;

  Swift

      var iconTranslationAnchor: NSExpression! { get set }

  View Source on GitHub
- `textColor`

  The color with which the text will be drawn.

  The default value of this property is an expression that evaluates to `UIColor.blackColor`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `UIColor` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textColor;

  Swift

      var textColor: NSExpression! { get set }

  View Source on GitHub
- `textColorTransition`

  The transition affecting any changes to this layer’s `textColor` property.

  This property corresponds to the `text-color-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textColorTransition;

  Swift

      var textColorTransition: MGLTransition { get set }

  View Source on GitHub
- `textHaloBlur`

  The halo’s fadeout distance towards the outside.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textHaloBlur;

  Swift

      var textHaloBlur: NSExpression! { get set }

  View Source on GitHub
- `textHaloBlurTransition`

  The transition affecting any changes to this layer’s `textHaloBlur` property.

  This property corresponds to the `text-halo-blur-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textHaloBlurTransition;

  Swift

      var textHaloBlurTransition: MGLTransition { get set }

  View Source on GitHub
- `textHaloColor`

  The color of the text’s halo, which helps it stand out from backgrounds.

  The default value of this property is an expression that evaluates to `UIColor.clearColor`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant `UIColor` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textHaloColor;

  Swift

      var textHaloColor: NSExpression! { get set }

  View Source on GitHub
- `textHaloColorTransition`

  The transition affecting any changes to this layer’s `textHaloColor` property.

  This property corresponds to the `text-halo-color-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textHaloColorTransition;

  Swift

      var textHaloColorTransition: MGLTransition { get set }

  View Source on GitHub
- `textHaloWidth`

  Distance of halo to the font outline. Max text halo width is ¼ of the font-size.

  This property is measured in points.

  The default value of this property is an expression that evaluates to the float `0`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values no less than 0
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textHaloWidth;

  Swift

      var textHaloWidth: NSExpression! { get set }

  View Source on GitHub
- `textHaloWidthTransition`

  The transition affecting any changes to this layer’s `textHaloWidth` property.

  This property corresponds to the `text-halo-width-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textHaloWidthTransition;

  Swift

      var textHaloWidthTransition: MGLTransition { get set }

  View Source on GitHub
- `textOpacity`

  The opacity at which the text will be drawn.

  The default value of this property is an expression that evaluates to the float `1`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  You can set this property to an expression containing any of the following:

  - Constant numeric values between 0 and 1 inclusive
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable and/or feature attributes

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textOpacity;

  Swift

      var textOpacity: NSExpression! { get set }

  View Source on GitHub
- `textOpacityTransition`

  The transition affecting any changes to this layer’s `textOpacity` property.

  This property corresponds to the `text-opacity-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textOpacityTransition;

  Swift

      var textOpacityTransition: MGLTransition { get set }

  View Source on GitHub
- `textTranslation`

  Distance that the text’s anchor is moved from its original placement.

  This property is measured in points.

  The default value of this property is an expression that evaluates to an `NSValue` object containing a `CGVector` struct set to 0 points rightward and 0 points downward. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-translate` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant `CGVector` values
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Interpolation and step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textTranslation;

  Swift

      var textTranslation: NSExpression! { get set }

  View Source on GitHub
- `textTranslationTransition`

  The transition affecting any changes to this layer’s `textTranslation` property.

  This property corresponds to the `text-translate-transition` property in the style JSON file format.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic) MGLTransition textTranslationTransition;

  Swift

      var textTranslationTransition: MGLTransition { get set }

  View Source on GitHub
- `textTranslationAnchor`

  Controls the frame of reference for `textTranslation`.

  The default value of this property is an expression that evaluates to `map`. Set this property to `nil` to reset it to the default value.

  This property is only applied to the style if `text` is non-`nil`, and `textTranslation` is non-`nil`. Otherwise, it is ignored.

  This attribute corresponds to the `text-translate-anchor` layout property in the Mapbox Style Specification.

  You can set this property to an expression containing any of the following:

  - Constant `MGLTextTranslationAnchor` values
  - Any of the following constant string values:
    - `map`: The text is translated relative to the map.
    - `viewport`: The text is translated relative to the viewport.
  - Predefined functions, including mathematical and string operators
  - Conditional expressions
  - Variable assignments and references to assigned variables
  - Step functions applied to the `$zoomLevel` variable

  This property does not support applying interpolation functions to the `$zoomLevel` variable or applying interpolation or step functions to feature attributes.

  #### Declaration

  Objective-C

      @property (assign, readwrite, nonatomic, null_resettable)
          NSExpression *textTranslationAnchor;

  Swift

      var textTranslationAnchor: NSExpression! { get set }

  View Source on GitHub