220 lines
9.8 KiB
Objective-C
220 lines
9.8 KiB
Objective-C
#import "MGLFeature.h"
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#import "MGLFoundation.h"
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#import "MGLTileSource.h"
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NS_ASSUME_NONNULL_BEGIN
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/**
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`MGLVectorSource` is a map content source that supplies tiled vector data in
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<a href="https://www.mapbox.com/vector-tiles/">Mapbox Vector Tile</a> format to
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be shown on the map. The location of and metadata about the tiles are defined
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either by an option dictionary or by an external file that conforms to the
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<a href="https://github.com/mapbox/tilejson-spec/">TileJSON specification</a>.
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A vector source is added to an `MGLStyle` object along with one or more
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`MGLVectorStyleLayer` objects. A vector style layer defines the appearance of
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any content supplied by the vector source.
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Each
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<a href="https://www.mapbox.com/mapbox-gl-style-spec/#sources-vector"><code>vector</code></a>
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source defined by the style JSON file is represented at runtime by an
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`MGLVectorSource` object that you can use to initialize new style layers. You
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can also add and remove sources dynamically using methods such as
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`-[MGLStyle addSource:]` and `-[MGLStyle sourceWithIdentifier:]`.
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Within each vector tile, each geometric coordinate must lie between
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−1 × <var>extent</var> and
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(<var>extent</var> × 2) − 1, inclusive. Any vector style
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layer initialized with a vector source must have a non-`nil` value in its
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`sourceLayerIdentifier` property.
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Commonly used vector sources include
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<a href="https://www.mapbox.com/vector-tiles/mapbox-streets/">Mapbox Streets</a>,
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<a href="https://www.mapbox.com/vector-tiles/mapbox-terrain/">Mapbox Terrain</a>,
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and
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<a href="https://www.mapbox.com/vector-tiles/mapbox-traffic-v1/">Mapbox Traffic</a>.
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### Example
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```swift
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let source = MGLVectorSource(identifier: "pois", tileURLTemplates: ["https://example.com/vector-tiles/{z}/{x}/{y}.mvt"], options: [
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.minimumZoomLevel: 9,
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.maximumZoomLevel: 16,
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.attributionInfos: [
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MGLAttributionInfo(title: NSAttributedString(string: "© Mapbox"), url: URL(string: "http://mapbox.com"))
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]
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])
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mapView.style?.addSource(source)
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```
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*/
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MGL_EXPORT
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@interface MGLVectorSource : MGLTileSource
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#pragma mark Initializing a Source
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/**
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Returns a vector source initialized with an identifier and configuration URL.
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After initializing and configuring the source, add it to a map view’s style
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using the `-[MGLStyle addSource:]` method.
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The URL may be a full HTTP or HTTPS URL or, for tile sets hosted by Mapbox, a
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Mapbox URL indicating a map identifier (`mapbox://<mapid>`). The URL should
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point to a JSON file that conforms to the
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<a href="https://github.com/mapbox/tilejson-spec/">TileJSON specification</a>.
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@param identifier A string that uniquely identifies the source in the style to
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which it is added.
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@param configurationURL A URL to a TileJSON configuration file describing the
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source’s contents and other metadata.
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@return An initialized vector source.
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*/
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- (instancetype)initWithIdentifier:(NSString *)identifier configurationURL:(NSURL *)configurationURL NS_DESIGNATED_INITIALIZER;
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/**
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Returns a vector source initialized an identifier, tile URL templates, and
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options.
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After initializing and configuring the source, add it to a map view’s style
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using the `-[MGLStyle addSource:]` method.
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#### Tile URL templates
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Tile URL templates are strings that specify the URLs of the tile images to
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load. Each template resembles an absolute URL, but with any number of
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placeholder strings that the source evaluates based on the tile it needs to
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load. For example:
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<ul>
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<li><code>http://www.example.com/tiles/{z}/{x}/{y}.pbf</code> could be
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evaluated as <code>http://www.example.com/tiles/14/6/9.pbf</code>.</li>
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<li><code>http://www.example.com/tiles/{z}/{x}/{y}{ratio}.png</code> could be
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evaluated as <code>http://www.example.com/tiles/14/6/9@2x.png</code>.</li>
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</ul>
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Tile sources support the following placeholder strings in tile URL templates,
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all of which are optional:
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<table>
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<thead>
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<tr><th>Placeholder string</th><th>Description</th></tr>
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</thead>
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<tbody>
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<tr>
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<td><code>{x}</code></td>
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<td>The index of the tile along the map’s x axis according to Spherical
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Mercator projection. If the value is 0, the tile’s left edge corresponds
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to the 180th meridian west. If the value is 2<sup><var>z</var></sup>−1,
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the tile’s right edge corresponds to the 180th meridian east.</td>
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</tr>
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<tr>
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<td><code>{y}</code></td>
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<td>The index of the tile along the map’s y axis according to Spherical
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Mercator projection. If the value is 0, the tile’s tile edge corresponds
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to arctan(sinh(π)), or approximately 85.0511 degrees north. If the value
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is 2<sup><var>z</var></sup>−1, the tile’s bottom edge corresponds to
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−arctan(sinh(π)), or approximately 85.0511 degrees south. The y axis is
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inverted if the <code>options</code> parameter contains
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<code>MGLTileSourceOptionTileCoordinateSystem</code> with a value of
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<code>MGLTileCoordinateSystemTMS</code>.</td>
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</tr>
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<tr>
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<td><code>{z}</code></td>
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<td>The tile’s zoom level. At zoom level 0, each tile covers the entire
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world map; at zoom level 1, it covers ¼ of the world; at zoom level 2,
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<sup>1</sup>⁄<sub>16</sub> of the world, and so on. For tiles loaded by
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a <code>MGLRasterSource</code> object, whether the tile zoom level
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matches the map’s current zoom level depends on the value of the
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source’s tile size as specified in the
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<code>MGLTileSourceOptionTileSize</code> key of the
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<code>options</code> parameter.</td>
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</tr>
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<tr>
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<td><code>{bbox-epsg-3857}</code></td>
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<td>The tile’s bounding box, expressed as a comma-separated list of the
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tile’s western, southern, eastern, and northern extents according to
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Spherical Mercator (EPSG:3857) projection. The bounding box is typically
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used with map services conforming to the
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<a href="http://www.opengeospatial.org/standards/wms">Web Map Service</a>
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protocol.</td>
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</tr>
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<tr>
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<td><code>{quadkey}</code></td>
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<td>A quadkey indicating both the tile’s location and its zoom level. The
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quadkey is typically used with
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<a href="https://msdn.microsoft.com/en-us/library/bb259689.aspx">Bing Maps</a>.
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</td>
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</tr>
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<tr>
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<td><code>{ratio}</code></td>
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<td>A suffix indicating the resolution of the tile image. The suffix is the
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empty string for standard resolution displays and <code>@2x</code> for
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Retina displays, including displays for which
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<code>NSScreen.backingScaleFactor</code> or <code>UIScreen.scale</code>
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is 3.</td>
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</tr>
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<tr>
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<td><code>{prefix}</code></td>
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<td>Two hexadecimal digits chosen such that each visible tile has a
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different prefix. The prefix is typically used for domain sharding.</td>
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</tr>
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</tbody>
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</table>
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For more information about the `{x}`, `{y}`, and `{z}` placeholder strings,
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consult the
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<a href="https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames">OpenStreetMap Wiki</a>.
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@param identifier A string that uniquely identifies the source in the style to
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which it is added.
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@param tileURLTemplates An array of tile URL template strings. Only the first
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string is used; any additional strings are ignored.
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@param options A dictionary containing configuration options. See
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`MGLTileSourceOption` for available keys and values. Pass in `nil` to use
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the default values.
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@return An initialized tile source.
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*/
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- (instancetype)initWithIdentifier:(NSString *)identifier tileURLTemplates:(NS_ARRAY_OF(NSString *) *)tileURLTemplates options:(nullable NS_DICTIONARY_OF(MGLTileSourceOption, id) *)options NS_DESIGNATED_INITIALIZER;
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#pragma mark Accessing a Source’s Content
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/**
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Returns an array of map features loaded by this source, restricted to the given
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source layers and filtered by the given predicate.
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Each object in the returned array represents a feature loaded by the source and
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provides access to attributes specified as part of the loaded feature. The
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source loads a feature if the source is added to an `MGLMapView`’s style; that
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style has a layer that uses the source; and the map view has recently scrolled
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to the region containing the feature.
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Features come from tiled vector data that is converted to tiles internally, so
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feature geometries are clipped at tile boundaries and features may appear
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duplicated across tiles. For example, suppose part of a lengthy polyline
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representing a road has recently scrolled into view. The resulting array
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includes those parts of the road that lie within the map tiles that the source
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has loaded, even if the road extends into other tiles. The portion of the road
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within each map tile is included individually.
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Returned features may not necessarily be visible to the user at the time they
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are loaded: the style may contain a layer that forces the source’s tiles to
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load but filters out the features in question, preventing them from being
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drawn. To obtain only _visible_ features, use the
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`-[MGLMapView visibleFeaturesAtPoint:inStyleLayersWithIdentifiers:predicate:]`
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or
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`-[MGLMapView visibleFeaturesInRect:inStyleLayersWithIdentifiers:predicate:]`
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method.
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@param sourceLayerIdentifiers The source layers to include in the query. Only
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the features contained in these source layers are included in the returned
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array. This array may not be empty.
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@param predicate A predicate to filter the returned features. Use `nil` to
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include all loaded features.
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@return An array of objects conforming to the `MGLFeature` protocol that
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represent features loaded by the source that match the predicate.
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*/
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- (NS_ARRAY_OF(id <MGLFeature>) *)featuresInSourceLayersWithIdentifiers:(NS_SET_OF(NSString *) *)sourceLayerIdentifiers predicate:(nullable NSPredicate *)predicate NS_SWIFT_NAME(features(sourceLayerIdentifiers:predicate:));
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@end
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NS_ASSUME_NONNULL_END
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