From c57c0820b11755b97afdbd1946077fe93eea9a3c Mon Sep 17 00:00:00 2001
From: Jeff Verkoeyen <featherless@google.com>
Date: Thu, 14 Sep 2017 15:20:38 -0400
Subject: [PATCH] Fix bug where transitions would not complete if the
 presentation controller didn't implement the startWithContext method.

---
 src/private/MDMViewControllerTransitionCoordinator.m | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/private/MDMViewControllerTransitionCoordinator.m b/src/private/MDMViewControllerTransitionCoordinator.m
index 2d7bf30..d99201a 100644
--- a/src/private/MDMViewControllerTransitionCoordinator.m
+++ b/src/private/MDMViewControllerTransitionCoordinator.m
@@ -102,7 +102,8 @@ - (instancetype)initWithTransitions:(NSArray<NSObject<MDMTransition> *> *)origin
 
     _completionBlocks = [NSMutableArray array];
 
-    if (_presentationController) {
+    if (_presentationController
+        && [_presentationController respondsToSelector:@selector(startWithContext:)]) {
       _presentationContext =
           [[MDMViewControllerTransitionContext alloc] initWithTransition:nil
                                                                direction:direction