MGLLineStyleLayer
@interface MGLLineStyleLayer : MGLVectorStyleLayer
An MGLLineStyleLayer
is a style layer that renders one or more stroked polylines on the map.
Use a line style layer to configure the visual appearance of polyline or multipolyline features. These features can come from vector tiles loaded by an MGLVectorTileSource
object, or they can be MGLPolyline
, MGLPolylineFeature
, MGLMultiPolyline
, or MGLMultiPolylineFeature
instances in an MGLShapeSource
or MGLComputedShapeSource
object.
You can access an existing line 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 line style layer and add it to the style using a method such as -[MGLStyle addLayer:]
.
Example
let layer = MGLLineStyleLayer(identifier: "trails-path", source: trails)
layer.sourceLayerIdentifier = "trails"
layer.lineWidth = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'exponential', 1.5, %@)",
[14: 2,
18: 20])
layer.lineColor = NSExpression(forConstantValue: UIColor.brown)
layer.lineCap = NSExpression(forConstantValue: "round")
layer.predicate = NSPredicate(format: "%K == %@", "trail-type", "mountain-biking")
mapView.style?.addLayer(layer)
-initWithIdentifier:source:
Returns a line 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.
Accessing the Layout Attributes
lineCap
The display of line endings.
The default value of this property is an expression that evaluates to butt
. 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
MGLLineCap
values - Any of the following constant string values:
butt
: A cap with a squared-off end which is drawn to the exact endpoint of the line.round
: A cap with a rounded end which is drawn beyond the endpoint of the line at a radius of one-half of the line’s width and centered on the endpoint of the line.square
: A cap with a squared-off end which is drawn beyond the endpoint of the line at a distance of one-half of the line’s width.- 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineCap;
Swift
var lineCap: NSExpression! { get set }
lineJoin
The display of lines when joining.
The default value of this property is an expression that evaluates to miter
. 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
MGLLineJoin
values - Any of the following constant string values:
bevel
: A join with a squared-off end which is drawn beyond the endpoint of the line at a distance of one-half of the line’s width.round
: A join with a rounded end which is drawn beyond the endpoint of the line at a radius of one-half of the line’s width and centered on the endpoint of the line.miter
: A join with a sharp, angled corner which is drawn with the outer sides beyond the endpoint of the path until they meet.- 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineJoin;
Swift
var lineJoin: NSExpression! { get set }
lineMiterLimit
Used to automatically convert miter joins to bevel joins for sharp angles.
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 lineJoin
is set to an expression that evaluates to miter
. 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineMiterLimit;
Swift
var lineMiterLimit: NSExpression! { get set }
lineRoundLimit
Used to automatically convert round joins to miter joins for shallow angles.
The default value of this property is an expression that evaluates to the float 1.05
. Set this property to nil
to reset it to the default value.
This property is only applied to the style if lineJoin
is set to an expression that evaluates to round
. 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineRoundLimit;
Swift
var lineRoundLimit: NSExpression! { get set }
lineSortKey
Sorts features in ascending order based on this value. Features with a higher sort key will appear above features with a lower sort key.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineSortKey;
Swift
var lineSortKey: NSExpression! { get set }
Accessing the Paint Attributes
lineBlur
Blur applied to the line, in points.
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.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineBlur;
Swift
var lineBlur: NSExpression! { get set }
lineBlurTransition
The transition affecting any changes to this layer’s lineBlur
property.
This property corresponds to the line-blur-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineBlurTransition;
Swift
var lineBlurTransition: MGLTransition { get set }
lineColor
The color with which the line 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 linePattern
is set to 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineColor;
Swift
var lineColor: NSExpression! { get set }
lineColorTransition
The transition affecting any changes to this layer’s lineColor
property.
This property corresponds to the line-color-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineColorTransition;
Swift
var lineColorTransition: MGLTransition { get set }
lineDashPattern
Specifies the lengths of the alternating dashes and gaps that form the dash pattern. The lengths are later scaled by the line width. To convert a dash length to points, multiply the length by the current line width. Note that GeoJSON sources with lineMetrics: true
specified won’t render dashed lines to the expected scale. Also note that zoom-dependent expressions will be evaluated only at integer zoom levels.
This property is measured in line widths.
This property is only applied to the style if linePattern
is set to nil
. Otherwise, it is ignored.
This attribute corresponds to the line-dasharray
layout property in the GL Style Specification.
You can set this property to an expression containing any of the following:
- Constant array values no less than 0
- 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineDashPattern;
Swift
var lineDashPattern: NSExpression! { get set }
lineDashPatternTransition
The transition affecting any changes to this layer’s lineDashPattern
property.
This property corresponds to the line-dasharray-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineDashPatternTransition;
Swift
var lineDashPatternTransition: MGLTransition { get set }
lineGapWidth
Draws a line casing outside of a line’s actual path. Value indicates the width of the inner gap.
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.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineGapWidth;
Swift
var lineGapWidth: NSExpression! { get set }
lineGapWidthTransition
The transition affecting any changes to this layer’s lineGapWidth
property.
This property corresponds to the line-gap-width-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineGapWidthTransition;
Swift
var lineGapWidthTransition: MGLTransition { get set }
lineGradient
The color gradient with which the line will be drawn. This property only has an effect on lines defined by an MGLShapeSource
whose MGLShapeSourceOptionLineDistanceMetrics
option is set to YES
.
This property is only applied to the style if lineDasharray
is set to nil
, and linePattern
is set to nil
, and the data source requirements are met. 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
$lineProgress
variable
This property does not support applying interpolation or step functions to feature attributes.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineGradient;
Swift
var lineGradient: NSExpression! { get set }
lineOffset
The line’s offset. For linear features, a positive value offsets the line to the right, relative to the direction of the line, and a negative value to the left. For polygon features, a positive value results in an inset, and a negative value results in an outset.
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.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineOffset;
Swift
var lineOffset: NSExpression! { get set }
lineOffsetTransition
The transition affecting any changes to this layer’s lineOffset
property.
This property corresponds to the line-offset-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineOffsetTransition;
Swift
var lineOffsetTransition: MGLTransition { get set }
lineOpacity
The opacity at which the line 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.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineOpacity;
Swift
var lineOpacity: NSExpression! { get set }
lineOpacityTransition
The transition affecting any changes to this layer’s lineOpacity
property.
This property corresponds to the line-opacity-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineOpacityTransition;
Swift
var lineOpacityTransition: MGLTransition { get set }
linePattern
Name of image in style images to use for drawing image lines. For seamless patterns, image width must be a factor of two (2, 4, 8, …, 512).
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
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *linePattern;
Swift
var linePattern: NSExpression! { get set }
linePatternTransition
The transition affecting any changes to this layer’s linePattern
property.
This property corresponds to the line-pattern-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition linePatternTransition;
Swift
var linePatternTransition: MGLTransition { get set }
lineTranslation
The geometry’s offset.
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 attribute corresponds to the line-translate
layout property in the GL 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineTranslation;
Swift
var lineTranslation: NSExpression! { get set }
lineTranslationTransition
The transition affecting any changes to this layer’s lineTranslation
property.
This property corresponds to the line-translate-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineTranslationTransition;
Swift
var lineTranslationTransition: MGLTransition { get set }
lineTranslationAnchor
Controls the frame of reference for lineTranslation
.
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 lineTranslation
is non-nil
. Otherwise, it is ignored.
This attribute corresponds to the line-translate-anchor
layout property in the GL Style Specification.
You can set this property to an expression containing any of the following:
- Constant
MGLLineTranslationAnchor
values - Any of the following constant string values:
map
: The line is translated relative to the map.viewport
: The line 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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineTranslationAnchor;
Swift
var lineTranslationAnchor: NSExpression! { get set }
lineWidth
Stroke thickness.
This property is measured in points.
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.
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 (nonatomic, assign, unsafe_unretained, readwrite, null_resettable)
NSExpression *lineWidth;
Swift
var lineWidth: NSExpression! { get set }
lineWidthTransition
The transition affecting any changes to this layer’s lineWidth
property.
This property corresponds to the line-width-transition
property in the style JSON file format.
Declaration
Objective-C
@property (nonatomic, assign, unsafe_unretained, readwrite)
MGLTransition lineWidthTransition;
Swift
var lineWidthTransition: MGLTransition { get set }
iOS SDK
Examples
SDK JS Reference
- Annotations
- Appendices
- NSExpression(MGLAdditions)
- NSValue(MGLAdditions)
- NSValue(MGLCircleStyleLayerAdditions)
- NSValue(MGLFillExtrusionStyleLayerAdditions)
- NSValue(MGLFillStyleLayerAdditions)
- NSValue(MGLHillshadeStyleLayerAdditions)
- NSValue(MGLLineStyleLayerAdditions)
- NSValue(MGLRasterStyleLayerAdditions)
- NSValue(MGLSymbolStyleLayerAdditions)
- MGLAccountManager
- MGLAnnotationImage
- MGLAnnotationView
- MGLAttributedExpression
- MGLAttributionInfo
- MGLBackgroundStyleLayer
- MGLCircleStyleLayer
- MGLClockDirectionFormatter
- MGLCompassButton
- MGLCompassDirectionFormatter
- MGLComputedShapeSource
- MGLCoordinateFormatter
- MGLDistanceFormatter
- MGLFillExtrusionStyleLayer
- MGLFillStyleLayer
- MGLForegroundStyleLayer
- MGLHeatmapStyleLayer
- MGLHillshadeStyleLayer
- MGLImageSource
- MGLLight
- MGLLineStyleLayer
- MGLLoggingConfiguration
- MGLMapCamera
- MGLMapSnapshot
- MGLMapSnapshotOptions
- MGLMapSnapshotOverlay
- MGLMapSnapshotter
- MGLMapView
- MGLMultiPoint
- MGLMultiPolygon
- MGLMultiPolyline
- MGLNetworkConfiguration
- MGLOfflinePack
- MGLOfflineStorage
- MGLPointAnnotation
- MGLPointCollection
- MGLPolygon
- MGLPolyline
- MGLRasterStyleLayer
- MGLRasterTileSource
- MGLShape
- MGLShapeCollection
- MGLShapeOfflineRegion
- MGLShapeSource
- MGLSource
- MGLStyle
- MGLStyleLayer
- MGLSymbolStyleLayer
- MGLTilePyramidOfflineRegion
- MGLTileSource
- MGLUserLocation
- MGLUserLocationAnnotationView
- MGLUserLocationAnnotationViewStyle
- MGLVectorStyleLayer
- MGLVectorTileSource
- MGLAnnotationVerticalAlignment
- MGLAnnotationViewDragState
- MGLAttributionInfoStyle
- MGLCirclePitchAlignment
- MGLCircleScaleAlignment
- MGLCircleTranslationAnchor
- MGLDEMEncoding
- MGLErrorCode
- MGLFillExtrusionTranslationAnchor
- MGLFillTranslationAnchor
- MGLHillshadeIlluminationAnchor
- MGLIconAnchor
- MGLIconPitchAlignment
- MGLIconRotationAlignment
- MGLIconTextFit
- MGLIconTranslationAnchor
- MGLLightAnchor
- MGLLineCap
- MGLLineJoin
- MGLLineTranslationAnchor
- MGLLoggingLevel
- MGLMapDebugMaskOptions
- MGLOfflinePackState
- MGLOrnamentPosition
- MGLOrnamentVisibility
- MGLRasterResamplingMode
- MGLResourceKind
- MGLSymbolPlacement
- MGLSymbolZOrder
- MGLTextAnchor
- MGLTextJustification
- MGLTextPitchAlignment
- MGLTextRotationAlignment
- MGLTextTransform
- MGLTextTranslationAnchor
- MGLTextWritingMode
- MGLTileCoordinateSystem
- MGLUserTrackingMode
- Formatters
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- Offline Maps
- Other Categories
- Other Classes
- Other Constants
- Other Enumerations
- Other Functions
- Other Protocols
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- Other Type Definitions
- Primitive Shapes
- MGLAnnotation
- MGLCalloutView
- MGLCalloutViewDelegate
- MGLCluster
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- MGLLocationManager
- MGLLocationManagerDelegate
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- Style Content
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- Information for Style Authors
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- Info.plist Keys
- Migrating to Expressions
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- Tile URL Templates
- Working with GeoJSON Data