Remove pausing of file sources in background (#639)

This behavior was introduced in response to a crash in 2016, but has led
to watchdog terminations when apps enter the background. Subsequent
refactoring to the file source implementations makes this behavior
unnecessary. Equivalent behavior was also removed from Maps SDK v10
(mapbox-maps-ios).

platform/darwin/src/MGLOfflineStorage.mm

@@ -50,7 +50,6 @@ @interface MGLOfflineStorage ()
 @property (nonatomic) std::shared_ptr<mbgl::DatabaseFileSource> mbglDatabaseFileSource;
 @property (nonatomic) std::shared_ptr<mbgl::FileSource> mbglOnlineFileSource;
 @property (nonatomic) std::shared_ptr<mbgl::FileSource> mbglFileSource;
-@property (nonatomic, getter=isPaused) BOOL paused;
 @end
 
 @implementation MGLOfflineStorage {
@@ -63,10 +62,6 @@ + (instancetype)sharedOfflineStorage {
     static MGLOfflineStorage *sharedOfflineStorage;
     dispatch_once(&onceToken, ^{
         sharedOfflineStorage = [[self alloc] init];
-#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
-        [[NSNotificationCenter defaultCenter] addObserver:sharedOfflineStorage selector:@selector(unpauseFileSource:) name:UIApplicationWillEnterForegroundNotification object:nil];
-        [[NSNotificationCenter defaultCenter] addObserver:sharedOfflineStorage selector:@selector(pauseFileSource:) name:UIApplicationDidEnterBackgroundNotification object:nil];
-#endif
         [sharedOfflineStorage reloadPacks];
     });
 
@@ -80,28 +75,6 @@ + (instancetype)sharedOfflineStorage {
     return sharedOfflineStorage;
 }
 
-#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
-- (void)pauseFileSource:(__unused NSNotification *)notification {
-    if (self.isPaused) {
-        return;
-    }
-
-    _mbglOnlineFileSource->pause();
-    _mbglDatabaseFileSource->pause();
-    self.paused = YES;
-}
-
-- (void)unpauseFileSource:(__unused NSNotification *)notification {
-    if (!self.isPaused) {
-        return;
-    }
-
-    _mbglOnlineFileSource->resume();
-    _mbglDatabaseFileSource->resume();
-    self.paused = NO;
-}
-#endif
-
 - (void)setDelegate:(id<MGLOfflineStorageDelegate>)newValue {
     MGLLogDebug(@"Setting delegate: %@", newValue);
     _delegate = newValue;
@@ -188,7 +161,6 @@ - (instancetype)init {
 }
 
 - (void)dealloc {
-    [[NSNotificationCenter defaultCenter] removeObserver:self];
     [[MGLAccountManager sharedManager] removeObserver:self forKeyPath:@"apiBaseURL"];
     [[MGLAccountManager sharedManager] removeObserver:self forKeyPath:@"accessToken"];
 

platform/ios/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Mapbox welcomes participation and contributions from everyone. Please read [CONTRIBUTING.md](../../CONTRIBUTING.md) to get started.
 
+## main
+
+* Fixed watchdog termination caused by pausing file sources when entering the background. ([#639](https://github.com/mapbox/mapbox-gl-native-ios/pull/639))
+
 ## 6.4.0 - September 27, 2021
 
 This version does not support Apple Silicon Macs (arm64).