[ios, macos] Update and reformat documentation for runtime styling (#7475)

* [ios, macos] Optimized changelog for runtime styling

Changelog entries related to style JSON now lead off with the analogous portion of the runtime styling API.

* [ios, macos] Autolink cross-class property references in docs

jazzy can autolink `Class.property` references in documentation comments.

* [ios, macos] Removed extra blank lines

* [ios, macos] Corrected typo in MGLMultiPoint docs

* [ios, macos] Rewrote shape and feature docs

Rewrote documentation about MGLShape, its subclasses, and MGLFeature to emphasize runtime styling uses over annotation uses, associate each type with real-world concepts, cross-reference related style layer classes, and cross-reference related or easily confused shape classes. Links to the GeoJSON specification have been updated to RFC 7946.

* [ios, macos] Expanded style layer docs

With this change, documentation about style layer classes is nominally based on the documentation in the style specification. However, all the existing layer types’ documentation has been overridden to explain what the layer looks like, relate the layer to a real-world concept, and cross-reference related geometry classes. This change also corrects the description of MGLBackgroundStyleLayer, which erroneously stated that the identifier must be “background”, whereas that only happens to be true by default for Studio template styles.

* [ios, macos] Wrap style layer docs

* [ios, macos] Removed unused code

* [ios, macos] Corrected symbol references in docs

* [ios, macos] Corrected typo in abstract class exception

1 files changed, 46 insertions, 12 deletions

diff --git a/platform/darwin/src/MGLPolyline.h b/platform/darwin/src/MGLPolyline.h
index cb98df9a1b..429ba9cddc 100644
--- a/platform/darwin/src/MGLPolyline.h
+++ b/platform/darwin/src/MGLPolyline.h
@@ -9,10 +9,35 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /**
- The `MGLPolyline` class represents a shape consisting of one or more points
- that define connecting line segments. The points are connected end-to-end in
- the order they are provided. The first and last points are not connected to
- each other.
+ An `MGLPolyline` object represents a shape consisting of two or more vertices,
+ specified as `CLLocationCoordinate2D` instances, and the line segments that
+ connect them. For example, you could use an polyline to represent a road or the
+ path along which something moves.
+ 
+ You can add polyline shapes to the map by adding them to an `MGLShapeSource`
+ object. Configure the appearance of an `MGLShapeSource`’s or
+ `MGLVectorSource`’s polylines collectively using an `MGLLineStyleLayer` or
+ `MGLSymbolStyleLayer` object.
+ 
+ Alternatively, you can add a polyline overlay directly to a map view using the
+ `-[MGLMapView addAnnotation:]` or `-[MGLMapView addOverlay:]` method. Configure
+ a polyline overlay’s appearance using
+ `-[MGLMapViewDelegate mapView:strokeColorForShapeAnnotation:]` and
+ `-[MGLMapViewDelegate mapView:lineWidthForPolylineAnnotation:]`.
+ 
+ The vertices are automatically connected in the order in which you provide
+ them. The first and last vertices are not connected to each other, but you can
+ specify the same `CLLocationCoordinate2D` as the first and last vertices in
+ order to close the polyline. To fill the space within the shape, use an
+ `MGLPolygon` object. To group multiple polylines together in one shape, use an
+ `MGLMultiPolyline` or `MGLShapeCollection` object.
+ 
+ To make the polyline straddle the antimeridian, specify some longitudes less
+ than −180 degrees or greater than 180 degrees.
+ 
+ A polyline is known as a
+ <a href="https://tools.ietf.org/html/rfc7946#section-3.1.4">LineString</a>
+ geometry in GeoJSON.
  */
 @interface MGLPolyline : MGLMultiPoint <MGLOverlay>
 
@@ -30,14 +55,23 @@ NS_ASSUME_NONNULL_BEGIN
 @end
 
 /**
- The `MGLMultiPolyline` class represents a shape consisting of one or more
- polylines. For example, you could use an `MGLMultiPolyline` object to represent
- both sides of a divided highway (dual carriageway), excluding the median
- (central reservation): each carriageway would be a distinct `MGLPolyline`
- object.
- 
- @note `MGLMultiPolyline` objects cannot be added to a map view using
-    `-[MGLMapView addAnnotations:]` and related methods.
+ An `MGLMultiPolyline` object represents a shape consisting of one or more
+ polylines. For example, you could use a multipolyline shape to represent both
+ sides of a divided highway (dual carriageway), excluding the median (central
+ reservation): each carriageway would be a distinct `MGLPolyline` object.
+ 
+ You can add multipolyline shapes to the map by adding them to an
+ `MGLShapeSource` object. Configure the appearance of an `MGLShapeSource`’s or
+ `MGLVectorSource`’s multipolylines collectively using an `MGLLineStyleLayer` or
+ `MGLSymbolStyleLayer` object.
+ 
+ You cannot add an `MGLMultiPolyline` object directly to a map view using
+ `-[MGLMapView addAnnotation:]` or `-[MGLMapView addOverlay:]`. However, you can
+ add the `polylines` array’s items as overlays individually.
+ 
+ A multipolyline is known as a
+ <a href="https://tools.ietf.org/html/rfc7946#section-3.1.5">MultiLineString</a>
+ geometry in GeoJSON.
  */
 @interface MGLMultiPolyline : MGLShape <MGLOverlay>