Shuffle & Cleanup Stuff (#3080)

Source/Private/ASPendingStateController.h

@@ -0,0 +1,53 @@
+//
+//  ASPendingStateController.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//
+//  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+
+#import <Foundation/Foundation.h>
+#import <AsyncDisplayKit/ASBaseDefines.h>
+
+@class ASDisplayNode;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ A singleton that is responsible for applying changes to
+ UIView/CALayer properties of display nodes when they
+ have been set on background threads.
+ 
+ This controller will enqueue run-loop events to flush changes
+ but if you need them flushed now you can call `flush` from the main thread.
+ */
+AS_SUBCLASSING_RESTRICTED
+@interface ASPendingStateController : NSObject
+
++ (ASPendingStateController *)sharedInstance;
+
+@property (nonatomic, readonly) BOOL hasChanges;
+
+/**
+ Flush all pending states for nodes now. Any UIView/CALayer properties
+ that have been set in the background will be applied to their
+ corresponding views/layers before this method returns.
+ 
+ You must call this method on the main thread.
+ */
+- (void)flush;
+
+/**
+ Register this node as having pending state that needs to be copied
+ over to the view/layer. This is called automatically by display nodes
+ when their view/layer properties are set post-load on background threads.
+ */
+- (void)registerNode:(ASDisplayNode *)node;
+
+@end
+
+NS_ASSUME_NONNULL_END