Make `MGLOfflinePack` instances post notifications

This commit also gets rid of private `MGLOfflinePackDelegate` protocol.
`userInfo` dictionary in notification objects retain the `state` and
`progress` values for backwards compatibility. They can be removed in
later major release.

5 files changed, 30 insertions, 85 deletions

diff --git a/platform/darwin/src/MGLOfflinePack.mm b/platform/darwin/src/MGLOfflinePack.mm
index 218e32940d..60a7b55531 100644
--- a/platform/darwin/src/MGLOfflinePack.mm
+++ b/platform/darwin/src/MGLOfflinePack.mm
@@ -4,6 +4,8 @@
 #import "MGLOfflineRegion_Private.h"
 #import "MGLTilePyramidOfflineRegion.h"
 
+#import "NSValue+MGLAdditions.h"
+
 #include <mbgl/storage/default_file_source.hpp>
 
 /**
@@ -37,7 +39,6 @@ private:
 
 @interface MGLOfflinePack ()
 
-@property (nonatomic, weak, nullable) id <MGLOfflinePackDelegate> delegate;
 @property (nonatomic, nullable, readwrite) mbgl::OfflineRegion *mbglOfflineRegion;
 @property (nonatomic, readwrite) MGLOfflinePackProgress progress;
 
@@ -175,7 +176,29 @@ private:
     progress.maximumResourcesExpected = status.requiredResourceCountIsPrecise ? status.requiredResourceCount : UINT64_MAX;
     self.progress = progress;
 
-    [self.delegate offlinePack:self progressDidChange:progress];
+    NSDictionary *userInfo = @{MGLOfflinePackUserInfoKeyState: @(self.state),
+                               MGLOfflinePackUserInfoKeyProgress: [NSValue valueWithMGLOfflinePackProgress:progress]};
+
+    NSNotificationCenter *noteCenter = [NSNotificationCenter defaultCenter];
+    [noteCenter postNotificationName:MGLOfflinePackProgressChangedNotification
+                              object:self
+                            userInfo:userInfo];
+}
+
+- (void)didReceiveError:(NSError *)error {
+    NSDictionary *userInfo = @{ MGLOfflinePackUserInfoKeyError: error };
+    NSNotificationCenter *noteCenter = [NSNotificationCenter defaultCenter];
+    [noteCenter postNotificationName:MGLOfflinePackErrorNotification
+                              object:self
+                            userInfo:userInfo];
+}
+
+- (void)didReceiveMaximumAllowedMapboxTiles:(uint64_t)limit {
+    NSDictionary *userInfo = @{ MGLOfflinePackUserInfoKeyMaximumCount: @(limit) };
+    NSNotificationCenter *noteCenter = [NSNotificationCenter defaultCenter];
+    [noteCenter postNotificationName:MGLOfflinePackMaximumMapboxTilesReachedNotification
+                              object:self
+                            userInfo:userInfo];
 }
 
 NSError *MGLErrorFromResponseError(mbgl::Response::Error error) {
@@ -211,12 +234,12 @@ void MBGLOfflineRegionObserver::statusChanged(mbgl::OfflineRegionStatus status)
 
 void MBGLOfflineRegionObserver::responseError(mbgl::Response::Error error) {
     dispatch_async(dispatch_get_main_queue(), ^{
-        [pack.delegate offlinePack:pack didReceiveError:MGLErrorFromResponseError(error)];
+        [pack didReceiveError:MGLErrorFromResponseError(error)];
     });
 }
 
 void MBGLOfflineRegionObserver::mapboxTileCountLimitExceeded(uint64_t limit) {
     dispatch_async(dispatch_get_main_queue(), ^{
-        [pack.delegate offlinePack:pack didReceiveMaximumAllowedMapboxTiles:limit];
+        [pack didReceiveMaximumAllowedMapboxTiles:limit];
     });
 }
diff --git a/platform/darwin/src/MGLOfflinePack_Private.h b/platform/darwin/src/MGLOfflinePack_Private.h
index 65156b4e90..8a63152dca 100644
--- a/platform/darwin/src/MGLOfflinePack_Private.h
+++ b/platform/darwin/src/MGLOfflinePack_Private.h
@@ -4,19 +4,8 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-@protocol MGLOfflinePackDelegate;
-
 @interface MGLOfflinePack (Private)
 
-/**
- The pack’s delegate.
-
- You can use the offline pack delegate to be notified of any changes in the
- pack’s progress and of any errors while downloading. For more information, see
- the `MGLOfflinePackDelegate` documentation.
- */
-@property (nonatomic, weak, nullable) id <MGLOfflinePackDelegate> delegate;
-
 @property (nonatomic, nullable) mbgl::OfflineRegion *mbglOfflineRegion;
 
 @property (nonatomic, readwrite) MGLOfflinePackState state;
@@ -31,47 +20,4 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
-/**
- The `MGLOfflinePackDelegate` protocol defines methods that a delegate of an
- `MGLOfflinePack` object can optionally implement to be notified of any changes
- in the pack’s download progress and of any errors while downloading.
- */
-@protocol MGLOfflinePackDelegate <NSObject>
-
-/**
- Sent whenever the pack’s state or download progress changes. Every change to a
- field in the `progress` property corresponds to an invocation of this method.
-
- @param pack The pack whose state of progress changed.
- @param progress The updated progress. To get the updated state, refer to the
-    `state` property.
- */
-- (void)offlinePack:(MGLOfflinePack *)pack progressDidChange:(MGLOfflinePackProgress)progress;
-
-/**
- Sent whenever the pack encounters an error while downloading.
-
- Download errors may be recoverable. For example, this pack’s implementation may
- attempt to re-request failed resources based on an exponential backoff
- strategy or upon the restoration of network access.
-
- @param pack The pack that encountered an error.
- @param error A download error. For a list of possible error codes, see
-    `MGLErrorCode`.
- */
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveError:(NSError *)error;
-
-/**
- Sent when the maximum number of Mapbox-hosted tiles has been downloaded and
- stored on the current device.
-
- Once this limit is reached, no instance of `MGLOfflinePack` can download
- additional tiles from Mapbox APIs until already downloaded tiles are removed by
- calling the `-[MGLOfflineStorage removePack:withCompletionHandler:]` method.
- Contact your Mapbox sales representative to have the limit raised.
- */
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveMaximumAllowedMapboxTiles:(uint64_t)maximumCount;
-
-@end
-
 NS_ASSUME_NONNULL_END
diff --git a/platform/darwin/src/MGLOfflineStorage.mm b/platform/darwin/src/MGLOfflineStorage.mm
index bdecd101d2..af0f592902 100644
--- a/platform/darwin/src/MGLOfflineStorage.mm
+++ b/platform/darwin/src/MGLOfflineStorage.mm
@@ -26,7 +26,7 @@ NSString * const MGLOfflinePackErrorUserInfoKey = MGLOfflinePackUserInfoKeyError
 const MGLOfflinePackUserInfoKey MGLOfflinePackUserInfoKeyMaximumCount = @"MaximumCount";
 NSString * const MGLOfflinePackMaximumCountUserInfoKey = MGLOfflinePackUserInfoKeyMaximumCount;
 
-@interface MGLOfflineStorage () <MGLOfflinePackDelegate>
+@interface MGLOfflineStorage ()
 
 @property (nonatomic, strong, readwrite) NS_MUTABLE_ARRAY_OF(MGLOfflinePack *) *packs;
 @property (nonatomic) mbgl::DefaultFileSource *mbglFileSource;
@@ -197,7 +197,6 @@ NSString * const MGLOfflinePackMaximumCountUserInfoKey = MGLOfflinePackUserInfoK
         pack.state = MGLOfflinePackStateInactive;
         MGLOfflineStorage *strongSelf = weakSelf;
         [[strongSelf mutableArrayValueForKey:@"packs"] addObject:pack];
-        pack.delegate = strongSelf;
         if (completion) {
             completion(pack, error);
         }
@@ -269,10 +268,6 @@ NSString * const MGLOfflinePackMaximumCountUserInfoKey = MGLOfflinePackUserInfoK
             [pack invalidate];
         }
         self.packs = [packs mutableCopy];
-
-        for (MGLOfflinePack *pack in packs) {
-            pack.delegate = self;
-        }
     }];
 }
 
@@ -317,25 +312,4 @@ NSString * const MGLOfflinePackMaximumCountUserInfoKey = MGLOfflinePackUserInfoK
     return attributes.fileSize;
 }
 
-#pragma mark MGLOfflinePackDelegate methods
-
-- (void)offlinePack:(MGLOfflinePack *)pack progressDidChange:(__unused MGLOfflinePackProgress)progress {
-    [[NSNotificationCenter defaultCenter] postNotificationName:MGLOfflinePackProgressChangedNotification object:pack userInfo:@{
-        MGLOfflinePackUserInfoKeyState: @(pack.state),
-        MGLOfflinePackUserInfoKeyProgress: [NSValue valueWithMGLOfflinePackProgress:progress],
-    }];
-}
-
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveError:(NSError *)error {
-    [[NSNotificationCenter defaultCenter] postNotificationName:MGLOfflinePackErrorNotification object:pack userInfo:@{
-        MGLOfflinePackUserInfoKeyError: error,
-    }];
-}
-
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveMaximumAllowedMapboxTiles:(uint64_t)maximumCount {
-    [[NSNotificationCenter defaultCenter] postNotificationName:MGLOfflinePackMaximumMapboxTilesReachedNotification object:pack userInfo:@{
-        MGLOfflinePackUserInfoKeyMaximumCount: @(maximumCount),
-    }];
-}
-
 @end
diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 980a609483..9f0bc3af1c 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -24,6 +24,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 
 ### Other changes
 
+* `MGLOfflinePack` and `MGLOfflineStorage` now conform to standard notification posting patterns. Notifications are posted by `MGLOfflinePack` instances. `userInfo` dictionary still contains values with pack's `state` and `progress` properties for backwards compatibility. ([#7952](https://github.com/mapbox/mapbox-gl-native/pull/7952))
 * Fixed an issue where translucent, non-view-backed point annotations along tile boundaries would be drawn darker than expected. ([#6832](https://github.com/mapbox/mapbox-gl-native/pull/6832))
 * Fixed flickering that occurred when panning past the antimeridian. ([#7574](https://github.com/mapbox/mapbox-gl-native/pull/7574))
 * Fixed an issue that could prevent a cached style from appearing while the device is offline. ([#7770](https://github.com/mapbox/mapbox-gl-native/pull/7770))
diff --git a/platform/macos/CHANGELOG.md b/platform/macos/CHANGELOG.md
index e04ba3ced5..0e68a50e21 100644
--- a/platform/macos/CHANGELOG.md
+++ b/platform/macos/CHANGELOG.md
@@ -22,6 +22,7 @@
 
 ### Other changes
 
+* `MGLOfflinePack` and `MGLOfflineStorage` now conform to standard notification posting patterns. Notifications are posted by `MGLOfflinePack` instances. `userInfo` dictionary still contains values with pack's `state` and `progress` properties for backwards compatibility. ([#7952](https://github.com/mapbox/mapbox-gl-native/pull/7952))
 * Fixed an issue where translucent point annotations along tile boundaries would be drawn darker than expected. ([#6832](https://github.com/mapbox/mapbox-gl-native/pull/6832))
 * Fixed flickering that occurred when panning past the antimeridian. ([#7574](https://github.com/mapbox/mapbox-gl-native/pull/7574))
 * Fixed an issue that could prevent a cached style from appearing while the computer is offline. ([#7770](https://github.com/mapbox/mapbox-gl-native/pull/7770))