From 5dadab9aa681ade6f3b51d77d50c19aedfdfbb97 Mon Sep 17 00:00:00 2001
From: Krzysztof Magiera <krzys@swmansion.com>
Date: Thu, 20 Dec 2018 08:39:11 +0100
Subject: [PATCH] Trigger moveToWindow:nil call when screen animation starts to
 mimick UINavController behavior (#47)

With this change in the screens that are being transitioned get detach+attach events similarily to how it is done in UINavigationController. This allows views underneath to get notified that the transition is started and react to it when necessary (e.g. hide keyboard)
---
 ios/RNSScreenContainer.m | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/ios/RNSScreenContainer.m b/ios/RNSScreenContainer.m
index 810f6faa..23831db9 100644
--- a/ios/RNSScreenContainer.m
+++ b/ios/RNSScreenContainer.m
@@ -86,34 +86,46 @@
 - (void)updateContainer
 {
   _needUpdate = NO;
-  BOOL activeScreenChanged = NO;
+  BOOL activeScreenRemoved = NO;
   // remove screens that are no longer active
   NSMutableSet *orphaned = [NSMutableSet setWithSet:_activeScreens];
   for (RNSScreenView *screen in _reactSubviews) {
     if (!screen.active && [_activeScreens containsObject:screen]) {
-      activeScreenChanged = YES;
+      activeScreenRemoved = YES;
       [self detachScreen:screen];
     }
     [orphaned removeObject:screen];
   }
   for (RNSScreenView *screen in orphaned) {
-    activeScreenChanged = YES;
+    activeScreenRemoved = YES;
     [self detachScreen:screen];
   }
 
+  // detect if new screen is going to be activated
+  BOOL activeScreenAdded = NO;
+  for (RNSScreenView *screen in _reactSubviews) {
+    if (screen.active && ![_activeScreens containsObject:screen]) {
+      activeScreenAdded = YES;
+    }
+  }
+
   // add new screens in order they are placed in subviews array
   for (RNSScreenView *screen in _reactSubviews) {
     if (screen.active && ![_activeScreens containsObject:screen]) {
-      activeScreenChanged = YES;
+      [_activeScreens addObject:screen];
       [self attachScreen:screen];
-    } else if (screen.active) {
-      // if the view was already there we move it to "front" so that it is in the right
-      // order accoring to the subviews array
-      [_controller.view bringSubviewToFront:screen.controller.view];
+    } else if (screen.active && activeScreenAdded) {
+      // if we are adding new active screen, we perform remounting of all already marked as active
+      // this is done to mimick the effect UINavigationController has when willMoveToWindow:nil is
+      // triggered before the animation starts
+      if (activeScreenAdded) {
+        [self detachScreen:screen];
+        [self attachScreen:screen];
+      }
     }
   }
 
-  if (activeScreenChanged && _controller.presentedViewController == nil) {
+  if ((activeScreenRemoved || activeScreenAdded) && _controller.presentedViewController == nil) {
     // if user has reachability enabled (one hand use) and the window is slided down the below
     // method will force it to slide back up as it is expected to happen with UINavController when
     // we push or pop views.