[macos,ios] expose callback for transforming URLs

1 files changed, 60 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLOfflineStorage.h b/platform/darwin/src/MGLOfflineStorage.h
index 2d376c9222..16f134adb1 100644
--- a/platform/darwin/src/MGLOfflineStorage.h
+++ b/platform/darwin/src/MGLOfflineStorage.h
@@ -7,6 +7,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 @class MGLOfflinePack;
 @protocol MGLOfflineRegion;
+@protocol MGLOfflineStorageDelegate;
 
 /**
  Posted by the shared `MGLOfflineStorage` object when an `MGLOfflinePack`
@@ -132,6 +133,30 @@ typedef void (^MGLOfflinePackAdditionCompletionHandler)(MGLOfflinePack * _Nullab
 typedef void (^MGLOfflinePackRemovalCompletionHandler)(NSError * _Nullable error);
 
 /**
+ The type of resource that is requested.
+ */
+typedef NS_ENUM(NSUInteger, MGLResourceKind) {
+    /** Unknown type */
+    MGLResourceKindUnknown,
+    /** Style sheet JSON file */
+    MGLResourceKindStyle,
+    /** TileJSON file as specified in https://www.mapbox.com/mapbox-gl-js/style-spec/#root-sources */
+    MGLResourceKindSource,
+    /** A vector or raster tile as described in the style sheet at
+        https://www.mapbox.com/mapbox-gl-js/style-spec/#sources */
+    MGLResourceKindTile,
+    /** Signed distance field glyphs for text rendering. These are the URLs specified in the style
+        in https://www.mapbox.com/mapbox-gl-js/style-spec/#root-glyphs */
+    MGLResourceKindGlyphs,
+    /** Image part of a sprite sheet. It is constructed of the prefix in
+        https://www.mapbox.com/mapbox-gl-js/style-spec/#root-sprite and a PNG file extension. */
+    MGLResourceKindSpriteImage,
+    /** JSON part of a sprite sheet. It is constructed of the prefix in
+        https://www.mapbox.com/mapbox-gl-js/style-spec/#root-sprite and a JSON file extension. */
+    MGLResourceKindSpriteJSON,
+};
+
+/**
  MGLOfflineStorage implements a singleton (shared object) that manages offline
  packs. All of this class’s instance methods are asynchronous, reflecting the
  fact that offline resources are stored in a database. The shared object
@@ -145,6 +170,20 @@ MGL_EXPORT
  */
 + (instancetype)sharedOfflineStorage;
 
+#pragma mark - Accessing the Delegate
+
+/**
+ The receiver’s delegate.
+
+ An offline storage object sends messages to its delegate to allow it to
+ transform URLs before they are requested from the internet. This can be used
+ add or remove custom parameters, or reroute certain requests to other servers
+ or endpoints.
+ */
+@property(nonatomic, weak, nullable) IBOutlet id<MGLOfflineStorageDelegate> delegate;
+
+#pragma mark - Managing Offline Packs
+
 /**
  An array of all known offline packs, in the order in which they were created.
 
@@ -250,4 +289,25 @@ MGL_EXPORT
 
 @end
 
+/**
+ The `MGLOfflineStorageDelegate` protocol defines methods that a delegate of an
+ `MGLOfflineStorage` object can optionally implement to transform various types
+ of URLs before downloading them via the internet.
+ */
+@protocol MGLOfflineStorageDelegate <NSObject>
+
+/**
+ Sent whenever a URL needs to be transformed.
+
+ @param storage The storage object processing the download.
+ @param kind The kind of URL to be transformed.
+ @param url The original URL to be transformed.
+ @return A URL that will now be downloaded.
+ */
+- (NSURL *)offlineStorage:(MGLOfflineStorage *)storage
+     URLForResourceOfKind:(MGLResourceKind)kind
+                  withURL:(NSURL *)url;
+
+@end
+
 NS_ASSUME_NONNULL_END