Merge pull request #1300 from garrettmoon/skipClearContentsOnNodeMove

[ASDisplayNode] Don't clear contents when moving between parent nodes.

AsyncDisplayKit/ASDisplayNode.mm

@@ -1227,7 +1227,7 @@ static bool disableNotificationsForMovingBetweenParents(ASDisplayNode *from, ASD
   if (isMovingEquivalentParents) {
     [subnode __incrementVisibilityNotificationsDisabled];
   }
-  [subnode removeFromSupernode];
+  [subnode removeFromSupernodeMovingBetweenNodes:YES];
 
   if (!_subnodes)
     _subnodes = [[NSMutableArray alloc] init];
@@ -1497,6 +1497,11 @@ static NSInteger incrementIfFound(NSInteger i) {
 }
 
 - (void)removeFromSupernode
+{
+  [self removeFromSupernodeMovingBetweenNodes:NO];
+}
+
+- (void)removeFromSupernodeMovingBetweenNodes:(BOOL)movingBetweenNodes
 {
   ASDisplayNodeAssertThreadAffinity(self);
   BOOL shouldRemoveFromSuperviewOrSuperlayer = NO;
@@ -1505,7 +1510,7 @@ static NSInteger incrementIfFound(NSInteger i) {
     ASDN::MutexLocker l(_propertyLock);
     if (!_supernode)
       return;
-
+    
     // Check to ensure that our view or layer is actually inside of our supernode; otherwise, don't remove it.
     // Though _ASDisplayView decouples the supernode if it is inserted inside another view hierarchy, this is
     // more difficult to guarantee with _ASDisplayLayer because CoreAnimation doesn't have a -didMoveToSuperlayer.
@@ -1522,15 +1527,22 @@ static NSInteger incrementIfFound(NSInteger i) {
   // Do this before removing the view from the hierarchy, as the node will clear its supernode pointer when its view is removed from the hierarchy.
   // This call may result in the object being destroyed.
   [_supernode _removeSubnode:self];
-
+  
   if (shouldRemoveFromSuperviewOrSuperlayer) {
     ASPerformBlockOnMainThread(^{
       ASDN::MutexLocker l(_propertyLock);
+      
+      if (movingBetweenNodes) {
+        _flags.isMovingBetweenNodes = YES;
+      }
       if (_flags.layerBacked) {
         [_layer removeFromSuperlayer];
       } else {
         [_view removeFromSuperview];
       }
+      if (movingBetweenNodes) {
+        _flags.isMovingBetweenNodes = NO;
+      }
     });
   }
 }
@@ -1970,6 +1982,14 @@ void recursivelyTriggerDisplayForLayer(CALayer *layer, BOOL shouldBlock)
 - (void)clearContents
 {
   // No-op if these haven't been created yet, as that guarantees they don't have contents that needs to be released.
+  {
+    ASDN::MutexLocker l(_propertyLock);
+    //Do not clear contents if we're mearly moving between nodes
+    if (_flags.isMovingBetweenNodes) {
+      return;
+    }
+  }
+  
   _layer.contents = nil;
   _placeholderLayer.contents = nil;
   _placeholderImage = nil;

AsyncDisplayKit/Private/ASDisplayNodeInternal.h

@@ -82,6 +82,7 @@ FOUNDATION_EXPORT NSString * const ASRenderingEngineDidDisplayNodesScheduledBefo
     unsigned isEnteringHierarchy:1;
     unsigned isExitingHierarchy:1;
     unsigned isInHierarchy:1;
+    unsigned isMovingBetweenNodes:1;
     unsigned visibilityNotificationsDisabled:VISIBILITY_NOTIFICATIONS_DISABLED_BITS;
   } _flags;