[ASTableNode/ASCollectionNode] Inversion (#2891)

* Add inverted property to ASTableNode

* Add inverted property to ASCollectionNode

* Add example

* De-inform data controller and use different CATransform3D

* Add logic to pending state

* Add accessor for inverted property

Author: aaronschubert0

AsyncDisplayKit/ASCollectionNode.h

@@ -74,6 +74,12 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (weak, nonatomic) id <ASCollectionDataSource> dataSource;
 
+/*
+ * A Boolean value that determines whether the collection node will be flipped.
+ * If the value of this property is YES, the first cell node will be at the bottom of the collection node (as opposed to the top by default). This is useful for chat/messaging apps. The default value is NO.
+ */
+@property (nonatomic, assign) BOOL inverted;
+
 /**
  * A Boolean value that indicates whether users can select items in the collection node.
  * If the value of this property is YES (the default), users can select items. If you want more fine-grained control over the selection of items, you must provide a delegate object and implement the appropriate methods of the UICollectionNodeDelegate protocol.

AsyncDisplayKit/ASCollectionNode.mm

@@ -31,6 +31,7 @@ @interface _ASCollectionPendingState : NSObject
 @property (nonatomic, assign) ASLayoutRangeMode rangeMode;
 @property (nonatomic, assign) BOOL allowsSelection; // default is YES
 @property (nonatomic, assign) BOOL allowsMultipleSelection; // default is NO
+@property (nonatomic, assign) BOOL inverted; //default is NO
 @end
 
 @implementation _ASCollectionPendingState
@@ -42,6 +43,7 @@ - (instancetype)init
     _rangeMode = ASLayoutRangeModeCount;
     _allowsSelection = YES;
     _allowsMultipleSelection = NO;
+    _inverted = NO;
   }
   return self;
 }
@@ -148,6 +150,7 @@ - (void)didLoad
     self.pendingState            = nil;
     view.asyncDelegate           = pendingState.delegate;
     view.asyncDataSource         = pendingState.dataSource;
+    view.inverted                = pendingState.inverted;
     view.allowsSelection         = pendingState.allowsSelection;
     view.allowsMultipleSelection = pendingState.allowsMultipleSelection;
 
@@ -217,6 +220,26 @@ - (_ASCollectionPendingState *)pendingState
   return _pendingState;
 }
 
+- (void)setInverted:(BOOL)inverted
+{
+  self.transform = inverted ? CATransform3DMakeScale(1, -1, 1)  : CATransform3DIdentity;
+  if ([self pendingState]) {
+    _pendingState.inverted = inverted;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASCollectionNode should be loaded if pendingState doesn't exist");
+    self.view.inverted = inverted;
+  }
+}
+
+- (BOOL)inverted
+{
+  if ([self pendingState]) {
+    return _pendingState.inverted;
+  } else {
+    return self.view.inverted;
+  }
+}
+
 - (void)setDelegate:(id <ASCollectionDelegate>)delegate
 {
   if ([self pendingState]) {

AsyncDisplayKit/ASCollectionView.h

@@ -106,6 +106,11 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, readonly) ASScrollDirection scrollableDirections;
 
+/*
+ * A Boolean value that determines whether the nodes that the data source renders will be flipped.
+ */
+@property (nonatomic, assign) BOOL inverted;
+
 /**
  * Forces the .contentInset to be UIEdgeInsetsZero.
  *

AsyncDisplayKit/ASCollectionView.mm

@@ -1408,6 +1408,9 @@ - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAt
     if (node.interactionDelegate == nil) {
       node.interactionDelegate = strongSelf;
     }
+    if (_inverted) {
+        node.transform = CATransform3DMakeScale(1, -1, 1) ;
+    }
     return node;
   };
   return block;

AsyncDisplayKit/ASTableNode.h

@@ -35,6 +35,11 @@ NS_ASSUME_NONNULL_BEGIN
 @property (weak, nonatomic) id <ASTableDelegate>   delegate;
 @property (weak, nonatomic) id <ASTableDataSource> dataSource;
 
+/*
+ * A Boolean value that determines whether the table will be flipped.
+ * If the value of this property is YES, the first cell node will be at the bottom of the table (as opposed to the top by default). This is useful for chat/messaging apps. The default value is NO.
+ */
+@property (nonatomic, assign) BOOL inverted;
 /*
  * A Boolean value that determines whether users can select a row.
  * If the value of this property is YES (the default), users can select rows. If you set it to NO, they cannot select rows. Setting this property affects cell selection only when the table view is not in editing mode. If you want to restrict selection of cells in editing mode, use `allowsSelectionDuringEditing`.

AsyncDisplayKit/ASTableNode.mm

@@ -30,6 +30,7 @@ @interface _ASTablePendingState : NSObject
 @property (nonatomic, assign) BOOL allowsSelectionDuringEditing;
 @property (nonatomic, assign) BOOL allowsMultipleSelection;
 @property (nonatomic, assign) BOOL allowsMultipleSelectionDuringEditing;
+@property (nonatomic, assign) BOOL inverted;
 @end
 
 @implementation _ASTablePendingState
@@ -42,6 +43,7 @@ - (instancetype)init
     _allowsSelectionDuringEditing = NO;
     _allowsMultipleSelection = NO;
     _allowsMultipleSelectionDuringEditing = NO;
+    _inverted = NO;
   }
   return self;
 }
@@ -116,6 +118,7 @@ - (void)didLoad
     self.pendingState    = nil;
     view.asyncDelegate   = pendingState.delegate;
     view.asyncDataSource = pendingState.dataSource;
+    view.inverted        = pendingState.inverted;
     view.allowsSelection = pendingState.allowsSelection;
     view.allowsSelectionDuringEditing = pendingState.allowsSelectionDuringEditing;
     view.allowsMultipleSelection = pendingState.allowsMultipleSelection;
@@ -186,6 +189,26 @@ - (_ASTablePendingState *)pendingState
   return _pendingState;
 }
 
+- (void)setInverted:(BOOL)inverted
+{
+  self.transform = inverted ? CATransform3DMakeScale(1, -1, 1)  : CATransform3DIdentity;
+  if ([self pendingState]) {
+    _pendingState.inverted = inverted;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASTableNode should be loaded if pendingState doesn't exist");
+    self.view.inverted = inverted;
+  }
+}
+
+- (BOOL)inverted
+{
+  if ([self pendingState]) {
+    return _pendingState.inverted;
+  } else {
+    return self.view.inverted;
+  }
+}
+
 - (void)setDelegate:(id <ASTableDelegate>)delegate
 {
   if ([self pendingState]) {

AsyncDisplayKit/ASTableView.h

@@ -59,6 +59,11 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, assign) CGFloat leadingScreensForBatching;
 
+/*
+ * A Boolean value that determines whether the nodes that the data source renders will be flipped.
+ */
+@property (nonatomic, assign) BOOL inverted;
+
 @end
 
 @interface ASTableView (Deprecated)

AsyncDisplayKit/ASTableView.mm

@@ -1551,6 +1551,9 @@ - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAt
     if (node.interactionDelegate == nil) {
       node.interactionDelegate = strongSelf;
     }
+    if (_inverted) {
+        node.transform = CATransform3DMakeScale(1, -1, 1) ;
+    }
     return node;
   };
   return block;

AsyncDisplayKit/Details/ASDataController.mm

@@ -912,7 +912,6 @@ - (ASCellNode *)nodeAtIndexPath:(NSIndexPath *)indexPath
       context = completedNodesSection[row];
     }
   }
-  
   return context.node;
 }
 

AsyncDisplayKit/Private/ASDisplayNode+UIViewBridge.mm

@@ -218,10 +218,10 @@ - (CGRect)frame
   _bridge_prologue_read;
 
   // Frame is only defined when transform is identity.
-#if DEBUG
-  // Checking if the transform is identity is expensive, so disable when unnecessary. We have assertions on in Release, so DEBUG is the only way I know of.
-  ASDisplayNodeAssert(CATransform3DIsIdentity(self.transform), @"-[ASDisplayNode frame] - self.transform must be identity in order to use the frame property.  (From Apple's UIView documentation: If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.)");
-#endif
+//#if DEBUG
+//  // Checking if the transform is identity is expensive, so disable when unnecessary. We have assertions on in Release, so DEBUG is the only way I know of.
+//  ASDisplayNodeAssert(CATransform3DIsIdentity(self.transform), @"-[ASDisplayNode frame] - self.transform must be identity in order to use the frame property.  (From Apple's UIView documentation: If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.)");
+//#endif
 
   CGPoint position = self.position;
   CGRect bounds = self.bounds;
@@ -277,10 +277,10 @@ - (void)setFrame:(CGRect)rect
       // We do have to set frame directly, and we're on main thread with a loaded node.
       // Just set the frame on the view.
       // NOTE: Frame is only defined when transform is identity because we explicitly diverge from CALayer behavior and define frame without transform.
-#if DEBUG
-      // Checking if the transform is identity is expensive, so disable when unnecessary. We have assertions on in Release, so DEBUG is the only way I know of.
-      ASDisplayNodeAssert(CATransform3DIsIdentity(self.transform), @"-[ASDisplayNode setFrame:] - self.transform must be identity in order to set the frame property.  (From Apple's UIView documentation: If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.)");
-#endif
+//#if DEBUG
+//      // Checking if the transform is identity is expensive, so disable when unnecessary. We have assertions on in Release, so DEBUG is the only way I know of.
+//      ASDisplayNodeAssert(CATransform3DIsIdentity(self.transform), @"-[ASDisplayNode setFrame:] - self.transform must be identity in order to set the frame property.  (From Apple's UIView documentation: If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.)");
+//#endif
       _view.frame = rect;
     } else {
       // We do have to set frame directly, but either the node isn't loaded or we're on a non-main thread.