Fix using UIActivityIndicatorView provided in view block (#2522)

Author: maicki

AsyncDisplayKit/ASDisplayNode.mm

@@ -495,7 +495,7 @@ - (UIView *)_viewToLoad
   }
 
   // Update flags related to special handling of UIImageView layers. More details on the flags
-  if (_flags.synchronous && [_viewClass isSubclassOfClass:[UIImageView class]]) {
+  if (_flags.synchronous && ([_viewClass isSubclassOfClass:[UIImageView class]] || [_viewClass isSubclassOfClass:[UIActivityIndicatorView class]])) {
     _flags.canClearContentsOfLayer = NO;
     _flags.canCallSetNeedsDisplayOfLayer = NO;
   }

examples/Swift/Sample/TailLoadingCellNode.swift

@@ -40,8 +40,6 @@ final class TailLoadingCellNode: ASCellNode {
 
   override func layoutSpecThatFits(constrainedSize: ASSizeRange) -> ASLayoutSpec {
 
-    spinner.style.flexBasis = ASDimensionMakeWithPoints(0.0)
-    
     return ASStackLayoutSpec(
       direction: .Horizontal,
       spacing: 16,
@@ -59,12 +57,13 @@ final class SpinnerNode: ASDisplayNode {
   override init() {
     super.init(viewBlock: { UIActivityIndicatorView(activityIndicatorStyle: .Gray) }, didLoadBlock: nil)
 
-    
-    self.style.height = ASDimensionMakeWithPoints(44.0)
+    // Set spinner node to default size of the activitiy indicator view
+    self.style.preferredSize = CGSizeMake(20.0, 20.0)
   }
 
   override func didLoad() {
     super.didLoad()
+    
     activityIndicatorView.startAnimating()
   }
 }

examples/Swift/Sample/ViewController.swift

@@ -55,7 +55,9 @@ final class ViewController: ASViewController, ASTableDataSource, ASTableDelegate
     let rowCount = self.tableNode(tableNode, numberOfRowsInSection: 0)
 
     if state.fetchingMore && indexPath.row == rowCount - 1 {
-      return TailLoadingCellNode()
+      let node = TailLoadingCellNode()
+      node.style.height = ASDimensionMake(44.0)
+      return node;
     }
 
     let node = ASTextCellNode()