Fixed a crash when the root view controller is UINavigationController and the user taps on a button that pushes a new view controller with 3 seconds timeframe when the BNCMatchView is added to primary window. Without this patch unloadViewController also removes the first view controller of the UINavigationController and eventually crashing the app. (#539)

Author: n8tr

Branch-SDK/Branch-SDK/BNCStrongMatchHelper.m

@@ -291,11 +291,13 @@ - (BOOL) willLoadViewControllerWithURL:(NSURL*)matchURL {
     self.matchView.alpha = 1.0;
     [self.matchView addSubview:self.matchViewController.view];
 
-    [self.primaryWindow.rootViewController addChildViewController:self.matchViewController];
-    UIView *parentView = self.primaryWindow.rootViewController.view ?: self.primaryWindow;
+    UIViewController *rootViewController = [self topViewController:self.primaryWindow.rootViewController];
+
+    [rootViewController addChildViewController:self.matchViewController];
+    UIView *parentView = rootViewController.view ?: self.primaryWindow;
     [parentView insertSubview:self.matchView atIndex:0];
 
-    [self.matchViewController didMoveToParentViewController:self.primaryWindow.rootViewController];
+    [self.matchViewController didMoveToParentViewController:rootViewController];
 
     return YES;
 }
@@ -319,6 +321,25 @@ - (void) unloadViewController {
     self.requestInProgress = NO;
 }
 
+/**
+  Find the top view controller that is not of type UINavigationController or UITabBarController
+ */
+- (UIViewController *)topViewController:(UIViewController *)baseViewController {
+    if ([baseViewController isKindOfClass:[UINavigationController class]]) {
+        return [self topViewController: ((UINavigationController *)baseViewController).visibleViewController];
+    }
+
+    if ([baseViewController isKindOfClass:[UITabBarController class]]) {
+        return [self topViewController: ((UITabBarController *)baseViewController).selectedViewController];
+    }
+
+    if ([baseViewController presentedViewController] != nil) {
+        return [self topViewController: [baseViewController presentedViewController]];
+    }
+
+    return baseViewController;
+}
+
 - (void)safariViewController:(SFSafariViewController *)controller
       didCompleteInitialLoad:(BOOL)didLoadSuccessfully {
     NSLog(@"Safari Did load. Success: %d.", didLoadSuccessfully);   //  eDebug