refs #892: Cocoa support for map ID style URLs

include/mbgl/ios/MGLMapView.h

@@ -33,6 +33,13 @@
 *   @return An initialized map view, or `nil` if the map view was unable to be initialized. */
 - (instancetype)initWithFrame:(CGRect)frame accessToken:(NSString *)accessToken bundledStyleNamed:(NSString *)styleName;
 
+/** Initialize a map view with a given frame, style URL, and access token.
+*   @param frame The frame with which to initialize the map view.
+*   @param accessToken A Mapbox API access token.
+*   @param styleURL The map style URL to use. Can be either an HTTP/HTTPS URL or a Mapbox map ID style URL (`mapbox://<user.style>`).
+*   @return An initialized map view, or `nil` if the map view was unable to be initialized. */
+- (instancetype)initWithFrame:(CGRect)frame accessToken:(NSString *)accessToken styleURL:(NSURL *)styleURL;
+
 /** Initialize a map view with a given frame, the default style, and an access token.
 *   @param frame The frame with which to initialize the map view.
 *   @param accessToken A Mapbox API access token.

platform/ios/MGLMapView.mm

@@ -132,6 +132,19 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     return self;
 }
 
+- (instancetype)initWithFrame:(CGRect)frame accessToken:(NSString *)accessToken styleURL:(NSURL *)styleURL
+{
+    self = [super initWithFrame:frame];
+
+    if (self && [self commonInit])
+    {
+        if (accessToken) [self setAccessToken:accessToken];
+        if (styleURL) [self setStyleURL:[styleURL absoluteString]];
+    }
+
+    return self;
+}
+
 - (instancetype)initWithFrame:(CGRect)frame accessToken:(NSString *)accessToken
 {
     return [self initWithFrame:frame accessToken:accessToken styleJSON:nil];