Add a Convenience Property to Get Owning View Controller (#3076)

* Add a convenience property -closestViewController

* Address comments

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -307,6 +307,8 @@
 		CC034A101E60C9BF00626263 /* ASRectTableTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CC034A0F1E60C9BF00626263 /* ASRectTableTests.m */; };
 		CC034A131E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.h in Headers */ = {isa = PBXBuildFile; fileRef = CC034A111E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.h */; };
 		CC034A141E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.m in Sources */ = {isa = PBXBuildFile; fileRef = CC034A121E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.m */; };
+		CC034A091E60BEB400626263 /* ASDisplayNode+Convenience.h in Headers */ = {isa = PBXBuildFile; fileRef = CC034A071E60BEB400626263 /* ASDisplayNode+Convenience.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		CC034A0A1E60BEB400626263 /* ASDisplayNode+Convenience.m in Sources */ = {isa = PBXBuildFile; fileRef = CC034A081E60BEB400626263 /* ASDisplayNode+Convenience.m */; };
 		CC051F1F1D7A286A006434CB /* ASCALayerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CC051F1E1D7A286A006434CB /* ASCALayerTests.m */; };
 		CC0AEEA41D66316E005D1C78 /* ASUICollectionViewTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CC0AEEA31D66316E005D1C78 /* ASUICollectionViewTests.m */; };
 		CC0F885B1E42807F00576FED /* ASCollectionViewFlowLayoutInspector.m in Sources */ = {isa = PBXBuildFile; fileRef = CC0F88591E42807F00576FED /* ASCollectionViewFlowLayoutInspector.m */; };
@@ -697,6 +699,8 @@
 		CC034A0F1E60C9BF00626263 /* ASRectTableTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASRectTableTests.m; sourceTree = "<group>"; };
 		CC034A111E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "AsyncDisplayKit+IGListKitMethods.h"; sourceTree = "<group>"; };
 		CC034A121E649F1300626263 /* AsyncDisplayKit+IGListKitMethods.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "AsyncDisplayKit+IGListKitMethods.m"; sourceTree = "<group>"; };
+		CC034A071E60BEB400626263 /* ASDisplayNode+Convenience.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASDisplayNode+Convenience.h"; sourceTree = "<group>"; };
+		CC034A081E60BEB400626263 /* ASDisplayNode+Convenience.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "ASDisplayNode+Convenience.m"; sourceTree = "<group>"; };
 		CC051F1E1D7A286A006434CB /* ASCALayerTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASCALayerTests.m; sourceTree = "<group>"; };
 		CC0AEEA31D66316E005D1C78 /* ASUICollectionViewTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASUICollectionViewTests.m; sourceTree = "<group>"; };
 		CC0F88591E42807F00576FED /* ASCollectionViewFlowLayoutInspector.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASCollectionViewFlowLayoutInspector.m; sourceTree = "<group>"; };
@@ -900,6 +904,8 @@
 				90FC784E1E4BFE1B00383C5A /* ASDisplayNode+Yoga.mm */,
 				683489271D70DE3400327501 /* ASDisplayNode+Deprecated.h */,
 				058D09DA195D050800B7D73C /* ASDisplayNode+Subclasses.h */,
+				CC034A071E60BEB400626263 /* ASDisplayNode+Convenience.h */,
+				CC034A081E60BEB400626263 /* ASDisplayNode+Convenience.m */,
 				058D09DB195D050800B7D73C /* ASDisplayNodeExtras.h */,
 				058D09DC195D050800B7D73C /* ASDisplayNodeExtras.mm */,
 				0587F9BB1A7309ED00AFF0BA /* ASEditableTextNode.h */,
@@ -1453,6 +1459,7 @@
 				698DFF471E36B7E9002891F1 /* ASLayoutSpecUtilities.h in Headers */,
 				9C70F20D1CDBE9CB007D6C76 /* ASDefaultPlayButton.h in Headers */,
 				DE7EF4F81DFF77720082B84A /* ASDisplayNode+FrameworkSubclasses.h in Headers */,
+				CC034A091E60BEB400626263 /* ASDisplayNode+Convenience.h in Headers */,
 				254C6B7E1BF94DF4003EC431 /* ASTextKitTailTruncater.h in Headers */,
 				B35062491B010EFD0018CF92 /* _ASCoreAnimationExtras.h in Headers */,
 				68EE0DBE1C1B4ED300BA1B99 /* ASMainSerialQueue.h in Headers */,
@@ -1916,6 +1923,7 @@
 				696F01EE1DD2AF450049FBD5 /* ASEventLog.mm in Sources */,
 				9C70F2051CDA4F06007D6C76 /* ASTraitCollection.m in Sources */,
 				83A7D95B1D44547700BF333E /* ASWeakMap.m in Sources */,
+				CC034A0A1E60BEB400626263 /* ASDisplayNode+Convenience.m in Sources */,
 				DE84918E1C8FFF9F003D89E9 /* ASRunLoopQueue.mm in Sources */,
 				68FC85E51CE29B7E00EDD713 /* ASTabBarController.m in Sources */,
 				34EFC7741B701D0A00AD841F /* ASAbsoluteLayoutSpec.mm in Sources */,

Source/ASDisplayNode+Convenience.h

@@ -0,0 +1,27 @@
+//
+//  ASDisplayNode+Convenience.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/24/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import <AsyncDisplayKit/ASDisplayNode.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class UIViewController;
+
+@interface ASDisplayNode (Convenience)
+
+/**
+ * @abstract Returns the view controller nearest to this node in the view hierarchy.
+ *
+ * @warning This property may only be accessed on the main thread. This property may
+ *   be @c nil until the node's view is actually hosted in the view hierarchy.
+ */
+@property (nonatomic, nullable, readonly) __kindof UIViewController *closestViewController;
+
+@end
+
+NS_ASSUME_NONNULL_END

Source/ASDisplayNode+Convenience.m

@@ -0,0 +1,39 @@
+//
+//  ASDisplayNode+Convenience.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/24/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import "ASDisplayNode+Convenience.h"
+
+#import <UIKit/UIViewController.h>
+
+#import <AsyncDisplayKit/ASDisplayNodeExtras.h>
+#import <AsyncDisplayKit/ASResponderChainEnumerator.h>
+
+@implementation ASDisplayNode (Convenience)
+
+- (__kindof UIViewController *)closestViewController
+{
+  ASDisplayNodeAssertMainThread();
+  
+  // Careful not to trigger node loading here.
+  if (!self.nodeLoaded) {
+    return nil;
+  }
+
+  // Get the closest view.
+  UIView *view = ASFindClosestViewOfLayer(self.layer);
+  // Travel up the responder chain to find a view controller.
+  for (UIResponder *responder in [view asdk_responderChainEnumerator]) {
+    UIViewController *vc = ASDynamicCast(responder, UIViewController);
+    if (vc != nil) {
+      return vc;
+    }
+  }
+  return nil;
+}
+
+@end

Source/ASDisplayNodeExtras.h

@@ -130,6 +130,11 @@ extern __kindof ASDisplayNode * _Nullable ASDisplayNodeFindFirstSupernodeOfClass
  */
 extern UIWindow * _Nullable ASFindWindowOfLayer(CALayer *layer) AS_WARN_UNUSED_RESULT;
 
+/**
+ * Given a layer, find the closest view it lives in, if any.
+ */
+extern UIView * _Nullable ASFindClosestViewOfLayer(CALayer *layer) AS_WARN_UNUSED_RESULT;
+
 /**
  * Given two nodes, finds their most immediate common parent.  Used for geometry conversion methods.
  * NOTE: It is an error to try to convert between nodes which do not share a common ancestor. This behavior is

Source/ASDisplayNodeExtras.mm

@@ -251,13 +251,19 @@ static inline BOOL _ASDisplayNodeIsAncestorOfDisplayNode(ASDisplayNode *possible
 
 extern UIWindow * _Nullable ASFindWindowOfLayer(CALayer *layer)
 {
-  while (layer != nil) {
+  UIView *view = ASFindClosestViewOfLayer(layer);
-    if (UIView *view = ASDynamicCast(layer.delegate, UIView)) {
+  if (UIWindow *window = ASDynamicCast(view, UIWindow)) {
-      if ([view isKindOfClass:[UIWindow class]]) {
+    return window;
-        return (UIWindow *)view;
   } else {
     return view.window;
   }
+}
+
+extern UIView * _Nullable ASFindClosestViewOfLayer(CALayer *layer)
+{
+  while (layer != nil) {
+    if (UIView *view = ASDynamicCast(layer.delegate, UIView)) {
+      return view;
     }
     layer = layer.superlayer;
   }

Source/AsyncDisplayKit.h

@@ -9,6 +9,7 @@
 //
 
 #import <AsyncDisplayKit/ASDisplayNode.h>
+#import <AsyncDisplayKit/ASDisplayNode+Convenience.h>
 #import <AsyncDisplayKit/ASDisplayNodeExtras.h>
 
 #import <AsyncDisplayKit/ASControlNode.h>

Source/Private/ASResponderChainEnumerator.m

@@ -7,6 +7,7 @@
 //
 
 #import "ASResponderChainEnumerator.h"
+#import <AsyncDisplayKit/ASAssert.h>
 
 @implementation ASResponderChainEnumerator {
   UIResponder *_currentResponder;
@@ -14,6 +15,7 @@
 
 - (instancetype)initWithResponder:(UIResponder *)responder
 {
+  ASDisplayNodeAssertMainThread();
   if (self = [super init]) {
     _currentResponder = responder;
   }
@@ -24,6 +26,7 @@
 
 - (id)nextObject
 {
+  ASDisplayNodeAssertMainThread();
   id result = [_currentResponder nextResponder];
   _currentResponder = result;
   return result;