Bugfix/jstricker/single child transition crash

RZUtils/Components/RZSingleChildContainerViewController/RZSingleChildContainerViewController.h

@@ -81,3 +81,6 @@ typedef void (^RZSingleChildContainerViewControllerCompletionBlock)(void);
 - (UIView *)childContentContainerView;
 
 @end
+
+
+

RZUtils/Components/RZSingleChildContainerViewController/RZSingleChildContainerViewController.m

@@ -45,6 +45,7 @@ @interface RZSingleChildContainerAlphaTransitioner : NSObject <UIViewControllerA
 
 @end
 
+
 // -------
 
 @interface RZSingleChildContainerViewController ()
@@ -55,6 +56,8 @@ @interface RZSingleChildContainerViewController ()
 
 @property (weak, nonatomic) UIViewController *viewControllerOnWhichWeCalledBegin;
 
+@property (copy, nonatomic) void(^queuedPresentationBlock)();
+
 @end
 
 @implementation RZSingleChildContainerViewController
@@ -163,41 +166,50 @@ - (void)setContentViewController:(UIViewController *)viewController animated:(BO
 
 - (void)setContentViewController:(UIViewController *)viewController animated:(BOOL)animated completion:(RZSingleChildContainerViewControllerCompletionBlock)completion
 {
+    __weak __typeof(self) weakSelf = self
+    ;
     if ( self.isTransitioning ) {
-        [NSException raise:NSInternalInconsistencyException format:@"%@: Cannot start a transition while a transition is already in place.", [self class]];
+
+        self.queuedPresentationBlock = ^{
+            [weakSelf setContentViewController:viewController animated:animated completion:completion];
+        };
+
+        return;
     }
-
-    __weak __typeof(self) wself = self;
-
+
     // We need to set isTransitioning to NO once the transition completes.
     // Then we run the passed-in completion block if it is not nil.
     void (^compoundCompletion)(void) = ^{
         self.isTransitioning = NO;
         if ( completion ) {
             completion();
         }
+        if ( self.queuedPresentationBlock != nil ) {
+            self.queuedPresentationBlock();
+            self.queuedPresentationBlock = nil;
+        }
     };
 
     [self performBlockWhenViewLoaded:^{
         self.isTransitioning = YES;
-        UIViewController *currentChild = wself.currentContentViewController;
+        UIViewController *currentChild = weakSelf.currentContentViewController;
 
         if ( animated ) {
 
             [currentChild beginAppearanceTransition:NO animated:YES];
 
             [currentChild willMoveToParentViewController:nil];
-            [wself addChildViewController:viewController];
-            viewController.view.frame = [wself childContentContainerView].bounds;
+            [weakSelf addChildViewController:viewController];
+            viewController.view.frame = [weakSelf childContentContainerView].bounds;
             viewController.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
 
             [viewController beginAppearanceTransition:YES animated:YES];
 
-            RZSingleChildContainerTransitionContext *ctx = [[RZSingleChildContainerTransitionContext alloc] initWithContainerVC:wself
+            RZSingleChildContainerTransitionContext *ctx = [[RZSingleChildContainerTransitionContext alloc] initWithContainerVC:weakSelf
                                                                                                                          fromVC:currentChild
                                                                                                                            toVC:viewController
                                                                                                                      completion:compoundCompletion];
-            [wself.contentVCAnimatedTransition animateTransition:ctx];
+            [weakSelf.contentVCAnimatedTransition animateTransition:ctx];
         }
         else {
 
@@ -210,14 +222,14 @@ - (void)setContentViewController:(UIViewController *)viewController animated:(BO
             [currentChild removeFromParentViewController];
             [currentChild endAppearanceTransition];
 
-            [wself addChildViewController:viewController];
-            viewController.view.frame = [wself childContentContainerView].bounds;
+            [weakSelf addChildViewController:viewController];
+            viewController.view.frame = [weakSelf childContentContainerView].bounds;
             viewController.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
             if ( hasWindow ) {
                 [viewController beginAppearanceTransition:YES animated:NO];
             }
-            [[wself childContentContainerView] addSubview:viewController.view];
-            [viewController didMoveToParentViewController:wself];
+            [[weakSelf childContentContainerView] addSubview:viewController.view];
+            [viewController didMoveToParentViewController:weakSelf];
             if ( hasWindow ) {
                 [viewController endAppearanceTransition];
             }
@@ -376,4 +388,4 @@ - (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)
     return kRZSingleChildContainerAlphaTransitionerAnimationDuration;
 }
 
-@end
+@end