Merge pull request #1921 from facebook/AHRangeModeUpdatingIssues

[ASRangeController] Fix Major Range Mode Updating Issues

AsyncDisplayKit/ASCollectionNode.h

@@ -27,7 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
  * ASCollectionNode is a node based class that wraps an ASCollectionView. It can be used
  * as a subnode of another node, and provide room for many (great) features and improvements later on.
  */
-@interface ASCollectionNode : ASDisplayNode
+@interface ASCollectionNode : ASDisplayNode <ASRangeControllerUpdateRangeProtocol>
 
 - (instancetype)initWithCollectionViewLayout:(UICollectionViewLayout *)layout;
 - (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout;
@@ -111,8 +111,4 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
-@interface ASCollectionNode (ASRangeControllerUpdateRangeProtocol) <ASRangeControllerUpdateRangeProtocol>
-
-@end
-
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASDisplayNode+Beta.h

@@ -9,6 +9,7 @@
 //
 
 #import "ASContextTransitioning.h"
+#import "ASLayoutRangeType.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -116,6 +117,15 @@ ASDISPLAYNODE_EXTERN_C_END
  */
 - (void)hierarchyDisplayDidFinish;
 
+/**
+ * Only ASLayoutRangeModeVisibleOnly or ASLayoutRangeModeLowMemory are recommended.  Default is ASLayoutRangeModeVisibleOnly,
+ * because this is the only way to ensure an application will not have blank / flashing views as the user navigates back after
+ * a memory warning.  Apps that wish to use the more effective / aggressive ASLayoutRangeModeLowMemory may need to take steps
+ * to mitigate this behavior, including: restoring a larger range mode to the next controller before the user navigates there,
+ * enabling .neverShowPlaceholders on ASCellNodes so that the navigation operation is blocked on redisplay completing, etc.
+ */
++ (void)setRangeModeForMemoryWarnings:(ASLayoutRangeMode)rangeMode;
+
 @end
 
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASTableNode.h

@@ -22,7 +22,7 @@
  * ASTableNode is a node based class that wraps an ASTableView. It can be used
  * as a subnode of another node, and provide room for many (great) features and improvements later on.
  */
-@interface ASTableNode : ASDisplayNode
+@interface ASTableNode : ASDisplayNode <ASRangeControllerUpdateRangeProtocol>
 
 - (instancetype)init; // UITableViewStylePlain
 - (instancetype)initWithStyle:(UITableViewStyle)style;
@@ -34,7 +34,3 @@
 @property (weak, nonatomic) id <ASTableDataSource> dataSource;
 
 @end
-
-@interface ASTableNode (ASRangeControllerUpdateRangeProtocol) <ASRangeControllerUpdateRangeProtocol>
-
-@end

AsyncDisplayKit/ASViewController.h

@@ -64,7 +64,12 @@ typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitWindowSizeBlock)(C
 
 @interface ASViewController (ASRangeControllerUpdateRangeProtocol)
 
-/// Automatically adjust range mode based on view events if the containing node confirms to the ASRangeControllerUpdateRangeProtocol
+/**
+ * Automatically adjust range mode based on view events. If you set this to YES, the view controller or its node
+ * must conform to the ASRangeControllerUpdateRangeProtocol. 
+ *
+ * Default value is NO.
+ */
 @property (nonatomic, assign) BOOL automaticallyAdjustRangeModeBasedOnViewEvents;
 
 @end

AsyncDisplayKit/ASViewController.mm

@@ -27,6 +27,9 @@
   BOOL _automaticallyAdjustRangeModeBasedOnViewEvents;
   BOOL _parentManagesVisibilityDepth;
   NSInteger _visibilityDepth;
+  BOOL _selfConformsToRangeModeProtocol;
+  BOOL _nodeConformsToRangeModeProtocol;
+  BOOL _didCheckRangeModeProtocolConformance;
 }
 
 - (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
@@ -167,12 +170,25 @@ ASVisibilityDepthImplementation;
 - (void)updateCurrentRangeModeWithModeIfPossible:(ASLayoutRangeMode)rangeMode
 {
   if (!_automaticallyAdjustRangeModeBasedOnViewEvents) { return; }
-  if (![_node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)]) {
-    return;
+  
+  if (!_didCheckRangeModeProtocolConformance) {
+    _selfConformsToRangeModeProtocol = [self conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
+    _nodeConformsToRangeModeProtocol = [_node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
+    _didCheckRangeModeProtocolConformance = YES;
+    if (!_selfConformsToRangeModeProtocol && !_nodeConformsToRangeModeProtocol) {
+      NSLog(@"Warning: automaticallyAdjustRangeModeBasedOnViewEvents set to YES in %@, but range mode updating is not possible because neither view controller nor node %@ conform to ASRangeControllerUpdateRangeProtocol.", self, _node);
+    }
+  }
+  
+  if (_selfConformsToRangeModeProtocol) {
+    id<ASRangeControllerUpdateRangeProtocol> rangeUpdater = (id<ASRangeControllerUpdateRangeProtocol>)self;
+    [rangeUpdater updateCurrentRangeWithMode:rangeMode];
+  }
+  
+  if (_nodeConformsToRangeModeProtocol) {
+    id<ASRangeControllerUpdateRangeProtocol> rangeUpdater = (id<ASRangeControllerUpdateRangeProtocol>)_node;
+    [rangeUpdater updateCurrentRangeWithMode:rangeMode];
   }
-
-  id<ASRangeControllerUpdateRangeProtocol> updateRangeNode = (id<ASRangeControllerUpdateRangeProtocol>)_node;
-  [updateRangeNode updateCurrentRangeWithMode:rangeMode];
 }
 
 #pragma mark - Layout Helpers

AsyncDisplayKit/Details/ASRangeController.mm

@@ -599,3 +599,12 @@ static ASLayoutRangeMode __rangeModeForMemoryWarnings = ASLayoutRangeModeVisible
 }
 
 @end
+
+@implementation ASDisplayNode (RangeModeConfiguring)
+
++ (void)setRangeModeForMemoryWarnings:(ASLayoutRangeMode)rangeMode
+{
+  [ASRangeController setRangeModeForMemoryWarnings:rangeMode];
+}
+
+@end

AsyncDisplayKit/Details/ASRangeControllerUpdateRangeProtocol+Beta.h

@@ -18,21 +18,4 @@
  */
 - (void)updateCurrentRangeWithMode:(ASLayoutRangeMode)rangeMode;
 
-/**
- * Only ASLayoutRangeModeVisibleOnly or ASLayoutRangeModeLowMemory are recommended.  Default is ASLayoutRangeModeVisibleOnly,
- * because this is the only way to ensure an application will not have blank / flashing views as the user navigates back after
- * a memory warning.  Apps that wish to use the more effective / aggressive ASLayoutRangeModeLowMemory may need to take steps
- * to mitigate this behavior, including: restoring a larger range mode to the next controller before the user navigates there,
- * enabling .neverShowPlaceholders on ASCellNodes so that the navigation operation is blocked on redisplay completing, etc.
- */
-+ (void)setRangeModeForMemoryWarnings:(ASLayoutRangeMode)rangeMode;
-
 @end
-
-
-
-
-
-
-
-

AsyncDisplayKitTests/ASCollectionViewTests.m

@@ -13,6 +13,7 @@
 #import "ASCollectionDataController.h"
 #import "ASCollectionViewFlowLayoutInspector.h"
 #import "ASCellNode.h"
+#import "ASCollectionNode.h"
 
 @interface ASTextCellNodeWithSetSelectedCounter : ASTextCellNode
 
@@ -241,4 +242,14 @@
   XCTAssertTrue(ASRangeTuningParametersEqualToRangeTuningParameters(preloadParams, [collectionView tuningParametersForRangeType:ASLayoutRangeTypeFetchData]));
 }
 
+/**
+ * This may seem silly, but we had issues where the runtime sometimes wouldn't correctly report
+ * conformances declared on categories.
+ */
+- (void)testThatCollectionNodeConformsToExpectedProtocols
+{
+  ASCollectionNode *node = [[ASCollectionNode alloc] initWithFrame:CGRectZero collectionViewLayout:[[UICollectionViewFlowLayout alloc] init]];
+  XCTAssert([node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)]);
+}
+
 @end

AsyncDisplayKitTests/ASTableViewTests.m

@@ -15,6 +15,7 @@
 #import "ASDisplayNode+Subclasses.h"
 #import "ASChangeSetDataController.h"
 #import "ASCellNode.h"
+#import "ASTableNode.h"
 
 #define NumberOfSections 10
 #define NumberOfRowsPerSection 20
@@ -518,4 +519,14 @@
   }];
 }
 
+/**
+ * This may seem silly, but we had issues where the runtime sometimes wouldn't correctly report
+ * conformances declared on categories.
+ */
+- (void)testThatTableNodeConformsToExpectedProtocols
+{
+  ASTableNode *node = [[ASTableNode alloc] initWithStyle:UITableViewStylePlain];
+  XCTAssert([node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)]);
+}
+
 @end