Clean up node transition API

AsyncDisplayKit/ASDisplayNode+Beta.h

@@ -50,10 +50,18 @@
 - (void)didCompleteLayoutTransition:(id<ASContextTransitioning>)context;
 
 /**
- * @abstract Invalidates the current layout and begins a relayout of the node to the new layout returned in `calculateLayoutThatFits:`.
+ * @abstract Transitions the current layout with a new constrained size.
  *
- * @discussion Animation is optional, but will still proceed through the `transitionLayout` methods with `isAnimated == NO`.
+ * @discussion Animation is optional, but will still proceed through your `animateLayoutTransition` implementation with `isAnimated == NO`.
+ * If the passed constrainedSize is the the same as the node's current constrained size, this method is noop.
  */
 - (ASLayout *)transitionLayoutWithSizeRange:(ASSizeRange)constrainedSize animated:(BOOL)animated;
 
+/**
+ * @abstract Invalidates the current layout and begins a relayout of the node with the current `constrainedSize`.
+ *
+ * @discussion Animation is optional, but will still proceed through your `animateLayoutTransition` implementation with `isAnimated == NO`.
+ */
+- (ASLayout *)transitionLayoutWithAnimation:(BOOL)animated;
+
 @end

AsyncDisplayKit/ASDisplayNode.mm

@@ -675,9 +675,14 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
   return _pendingLayout;
 }
 
-- (ASLayout *)transitionLayoutWithSizeRange:(ASSizeRange)constrainedSize animated:(BOOL)animated
+- (ASLayout *)transitionLayoutWithAnimation:(BOOL)animated
 {
   [self invalidateCalculatedLayout];
+  [self transitionLayoutWithSizeRange:_constrainedSize animated:animated];
+}
+
+- (ASLayout *)transitionLayoutWithSizeRange:(ASSizeRange)constrainedSize animated:(BOOL)animated
+{
   return [self measureWithSizeRange:constrainedSize completion:^{
     _transitionContext = [[_ASTransitionContext alloc] initWithLayout:_pendingLayout
                                                       constrainedSize:constrainedSize

AsyncDisplayKit/ASViewController.m

@@ -59,6 +59,9 @@
 - (void)viewWillAppear:(BOOL)animated
 {
   [super viewWillAppear:animated];
+
+  [_node measureWithSizeRange:[self nodeConstrainedSize]];
+
   _ensureDisplayed = YES;
   [_node recursivelyFetchData];
 }