From b5c886232cbab9e4c8b5e46c0b76950cf08da627 Mon Sep 17 00:00:00 2001
From: Julian Rex <julian.rex@mapbox.com>
Date: Fri, 29 Mar 2019 00:34:13 -0400
Subject: [ios] Enable/disable presentsWithTransaction when moving to/from a
 window.

---
 platform/ios/src/MGLMapView.mm | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index c94cf477ef..89fc1e8fab 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -1234,12 +1234,35 @@ public:
 - (void)willMoveToWindow:(UIWindow *)newWindow {
     [super willMoveToWindow:newWindow];
     [self refreshSupportedInterfaceOrientationsWithWindow:newWindow];
+    
+    if (!newWindow)
+    {
+        // See https://github.com/mapbox/mapbox-gl-native/issues/14232
+        // In iOS 12.2, CAEAGLLayer.presentsWithTransaction can cause dramatic
+        // slow down. The exact cause of this is unknown, but this work around
+        // appears to lessen the effects.
+        //
+        // Also, consider calling the new mbgl::Renderer::flush()
+        CAEAGLLayer *eaglLayer = MGL_OBJC_DYNAMIC_CAST(_glView.layer, CAEAGLLayer);
+        eaglLayer.presentsWithTransaction = NO;
+        
+        // Moved from didMoveToWindow
+        [self validateDisplayLink];
+    }
 }
 
 - (void)didMoveToWindow
 {
-    [self validateDisplayLink];
     [super didMoveToWindow];
+    
+    if (self.window)
+    {
+        // See above comment
+        CAEAGLLayer *eaglLayer = MGL_OBJC_DYNAMIC_CAST(_glView.layer, CAEAGLLayer);
+        eaglLayer.presentsWithTransaction = YES;
+        
+        [self validateDisplayLink];
+    }
 }
 
 - (void)didMoveToSuperview
-- 
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