From e3091737cad01b2966785a1d01a5b3d4fb86b51a Mon Sep 17 00:00:00 2001
From: Garrett Moon <garrett@excitedpixel.com>
Date: Thu, 25 Aug 2016 21:18:04 -0700
Subject: [PATCH] Enable ASRangeControllerUpdateRangeProtocol by default if
 view controller or node support it. (#2133)

---
 AsyncDisplayKit/ASViewController.h  |  2 +-
 AsyncDisplayKit/ASViewController.mm | 21 +++++++++------------
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/AsyncDisplayKit/ASViewController.h b/AsyncDisplayKit/ASViewController.h
index 84bd14d604..5a620e24c8 100644
--- a/AsyncDisplayKit/ASViewController.h
+++ b/AsyncDisplayKit/ASViewController.h
@@ -68,7 +68,7 @@ typedef ASTraitCollection * _Nonnull (^ASDisplayTraitsForTraitWindowSizeBlock)(C
  * 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.
+ * Default value is YES *if* node or view controller conform to ASRangeControllerUpdateRangeProtocol otherwise it is NO.
  */
 @property (nonatomic, assign) BOOL automaticallyAdjustRangeModeBasedOnViewEvents;
 
diff --git a/AsyncDisplayKit/ASViewController.mm b/AsyncDisplayKit/ASViewController.mm
index dd29f17de4..af50c36283 100644
--- a/AsyncDisplayKit/ASViewController.mm
+++ b/AsyncDisplayKit/ASViewController.mm
@@ -29,7 +29,6 @@
   NSInteger _visibilityDepth;
   BOOL _selfConformsToRangeModeProtocol;
   BOOL _nodeConformsToRangeModeProtocol;
-  BOOL _didCheckRangeModeProtocolConformance;
 }
 
 - (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
@@ -54,7 +53,9 @@
   ASDisplayNodeAssertTrue(!node.layerBacked);
   _node = node;
 
-  _automaticallyAdjustRangeModeBasedOnViewEvents = NO;
+  _selfConformsToRangeModeProtocol = [self conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
+  _nodeConformsToRangeModeProtocol = [_node conformsToProtocol:@protocol(ASRangeControllerUpdateRangeProtocol)];
+  _automaticallyAdjustRangeModeBasedOnViewEvents = _selfConformsToRangeModeProtocol || _nodeConformsToRangeModeProtocol;
 
   return self;
 }
@@ -168,22 +169,18 @@ ASVisibilityDepthImplementation;
 
 - (void)setAutomaticallyAdjustRangeModeBasedOnViewEvents:(BOOL)automaticallyAdjustRangeModeBasedOnViewEvents
 {
-  _automaticallyAdjustRangeModeBasedOnViewEvents = automaticallyAdjustRangeModeBasedOnViewEvents;
+  if (automaticallyAdjustRangeModeBasedOnViewEvents != _automaticallyAdjustRangeModeBasedOnViewEvents) {
+    if (automaticallyAdjustRangeModeBasedOnViewEvents && _selfConformsToRangeModeProtocol == NO && _nodeConformsToRangeModeProtocol == NO) {
+      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);
+    }
+    _automaticallyAdjustRangeModeBasedOnViewEvents = automaticallyAdjustRangeModeBasedOnViewEvents;
+  }
 }
 
 - (void)updateCurrentRangeModeWithModeIfPossible:(ASLayoutRangeMode)rangeMode
 {
   if (!_automaticallyAdjustRangeModeBasedOnViewEvents) { 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];