From 33c16689a88aee234fd482baf854f6de96d34ddd Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@fb.com>
Date: Wed, 26 Aug 2020 18:47:28 -0700
Subject: [PATCH] Deallocate UIViewController after it was used in Modal
 component

Summary:
Changelog: [Internal]

# Problem
`RCTModalHostViewComponentView` reuses the same UIViewController between recycles. This can be a problem if dismissal of the modal is animated as the UIViewController is still presented while it is being dismissed. That's when "Application tried to present modally an active controller" exception can happen.

# Solution
Deallocate UIViewController when `RCTModalHostViewComponentView` is recycled.

Reviewed By: PeteTheHeat

Differential Revision: D23345711

fbshipit-source-id: da540571184afcb88b52758c4a1f0b4ec5874eb1
---
 .../Modal/RCTModalHostViewComponentView.mm    | 27 ++++++++++++-------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm b/React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm
index dfe980c3679..b4a8b7b2f52 100644
--- a/React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm
+++ b/React/Fabric/Mounting/ComponentViews/Modal/RCTModalHostViewComponentView.mm
@@ -111,15 +111,23 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
     static const auto defaultProps = std::make_shared<const ModalHostViewProps>();
     _props = defaultProps;
     _shouldAnimatePresentation = YES;
-    _viewController = [RCTFabricModalHostViewController new];
-    _viewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
-    _viewController.delegate = self;
+
     _isPresented = NO;
   }
 
   return self;
 }
 
+- (RCTFabricModalHostViewController *)viewController
+{
+  if (!_viewController) {
+    _viewController = [RCTFabricModalHostViewController new];
+    _viewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
+    _viewController.delegate = self;
+  }
+  return _viewController;
+}
+
 - (void)presentViewController:(UIViewController *)modalViewController
                      animated:(BOOL)animated
                    completion:(void (^)(void))completion
@@ -138,7 +146,7 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
   BOOL shouldBePresented = !_isPresented && self.window;
   if (shouldBePresented) {
     _isPresented = YES;
-    [self presentViewController:_viewController
+    [self presentViewController:self.viewController
                        animated:_shouldAnimatePresentation
                      completion:^{
                        if (!self->_eventEmitter) {
@@ -155,7 +163,7 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
   BOOL shouldBeHidden = _isPresented && !self.superview;
   if (shouldBeHidden) {
     _isPresented = NO;
-    [self dismissViewController:_viewController animated:_shouldAnimatePresentation];
+    [self dismissViewController:self.viewController animated:_shouldAnimatePresentation];
   }
 }
 
@@ -197,6 +205,7 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
 {
   [super prepareForRecycle];
   _stateTeller.invalidate();
+  _viewController = nil;
   _isPresented = NO;
 }
 
@@ -205,14 +214,14 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
   const auto &newProps = *std::static_pointer_cast<const ModalHostViewProps>(props);
 
 #if !TARGET_OS_TV
-  _viewController.supportedInterfaceOrientations = supportedOrientationsMask(newProps.supportedOrientations);
+  self.viewController.supportedInterfaceOrientations = supportedOrientationsMask(newProps.supportedOrientations);
 #endif
 
   std::tuple<BOOL, UIModalTransitionStyle> result = animationConfiguration(newProps.animationType);
   _shouldAnimatePresentation = std::get<0>(result);
-  _viewController.modalTransitionStyle = std::get<1>(result);
+  self.viewController.modalTransitionStyle = std::get<1>(result);
 
-  _viewController.modalPresentationStyle = presentationConfiguration(newProps);
+  self.viewController.modalPresentationStyle = presentationConfiguration(newProps);
 
   [super updateProps:props oldProps:oldProps];
 }
@@ -224,7 +233,7 @@ static ModalHostViewEventEmitter::OnOrientationChange onOrientationChangeStruct(
 
 - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
 {
-  [_viewController.view insertSubview:childComponentView atIndex:index];
+  [self.viewController.view insertSubview:childComponentView atIndex:index];
 }
 
 - (void)unmountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index