MBGLOfflineRegionObserver is owned by the offline database thread, and might be destroyed by the time the dispatch_async completes. Instead of implicitly capturing this, capture a copy of the MBGLOfflinePack weak pointer.
MBGLOfflineRegionObserver is owned by the offline database thread, and might be destroyed by the time the dispatch_async completes. Instead of implicitly capturing this, capture a copy of the MBGLOfflinePack weak pointer.