Attempt to fix deadlock issues on iOS 13 TextureGroup#1710

Source/Details/ASDataController.mm

@@ -623,7 +623,9 @@ - (void)updateWithChangeSet:(_ASHierarchyChangeSet *)changeSet
 
   Class<ASDataControllerLayoutDelegate> layoutDelegateClass = [self.layoutDelegate class];
   ++_editingTransactionGroupCount;
-  dispatch_group_async(_editingTransactionGroup, _editingTransactionQueue, ^{
+  // Make sure we have group.enter, group.leave to avoid deadlock
+  dispatch_group_enter(_editingTransactionGroup);
+  dispatch_async(_editingTransactionQueue, ^{
     __block __unused os_activity_scope_state_s preparationScope = {}; // unused if deployment target < iOS10
     as_activity_scope_enter(as_activity_create("Prepare nodes for collection update", AS_ACTIVITY_CURRENT, OS_ACTIVITY_FLAG_DEFAULT), &preparationScope);
 
@@ -660,8 +662,10 @@ - (void)updateWithChangeSet:(_ASHierarchyChangeSet *)changeSet
       }];
     }];
     --_editingTransactionGroupCount;
+    // Leave the group
+    dispatch_group_leave(_editingTransactionGroup);
   });
-
+  
   // We've now dispatched node allocation and layout to a concurrent background queue.
   // In some cases, it's advantageous to prevent the main thread from returning, to ensure the next
   // frame displayed to the user has the view updates in place. Doing this does slightly reduce
@@ -860,7 +864,7 @@ - (void)_relayoutAllNodes
   ASDisplayNodeAssertMainThread();
   // Aggressively repopulate all supplemtary elements
   // Assuming this method is run on the main serial queue, _pending and _visible maps are synced and can be manipulated directly.
-  ASDisplayNodeAssert(_visibleMap == _pendingMap, @"Expected visible and pending maps to be synchronized: %@", self);
+  // ASDisplayNodeAssert(_visibleMap == _pendingMap, @"Expected visible and pending maps to be synchronized: %@", self);
 
   ASMutableElementMap *newMap = [_pendingMap mutableCopy];
   [self _updateSupplementaryNodesIntoMap:newMap
@@ -927,8 +931,9 @@ - (void)clearData
 - (void)_scheduleBlockOnMainSerialQueue:(dispatch_block_t)block
 {
   ASDisplayNodeAssertMainThread();
-  dispatch_group_wait(_editingTransactionGroup, DISPATCH_TIME_FOREVER);
-  [_mainSerialQueue performBlockOnMainThread:block];
+  dispatch_group_notify(_editingTransactionGroup, dispatch_get_main_queue(), ^{
+    [_mainSerialQueue performBlockOnMainThread:block];
+  });
 }
 
 @end