Update with PR feedback

2 files changed, 9 insertions, 5 deletions

diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index cf14c50acc..2e2d74407d 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -24,7 +24,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 
 * Added `MGLOrnamentPosition` enum and margin properties to customize scale bar, compass, logo, and attribution position within the map view. ([#13911](https://github.com/mapbox/mapbox-gl-native/pull/13911))
 * Added an `MGLMapView.prefetchesTiles` property to configure lower-resolution tile prefetching behavior. ([#14031](https://github.com/mapbox/mapbox-gl-native/pull/14031))
-* Fixed a performance issue seen on iOS 12.2, when an `MGLMapView` is repeatedly removed and re-added in a view hierarchy. ([#14264](https://github.com/mapbox/mapbox-gl-native/pull/14264))
+* Speculatively fixed a performance issue seen on iOS 12.2, when an `MGLMapView` is repeatedly removed and re-added in a view hierarchy. ([#14264](https://github.com/mapbox/mapbox-gl-native/pull/14264))
 
 
 ## 4.9.0 - February 27, 2019
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 52e1febe15..2ec47b0bcd 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -156,6 +156,8 @@ const CGFloat MGLAnnotationImagePaddingForCallout = 1;
 
 const CGSize MGLAnnotationAccessibilityElementMinimumSize = CGSizeMake(10, 10);
 
+/// The number of view annotations (excluding the user location view) that must
+/// be descendents of `MGLMapView` before presentsWithTransaction is enabled.
 static const NSUInteger MGLPresentsWithTransactionAnnotationCount = 3;
 
 /// An indication that the requested annotation was not found or is nonexistent.
@@ -331,6 +333,9 @@ public:
     CFTimeInterval _frameCounterStartTime;
     NSInteger _frameCount;
     CFTimeInterval _frameDurations;
+    
+    BOOL _atLeastiOS_12_2_0;
+
 }
 
 #pragma mark - Setup & Teardown -
@@ -444,6 +449,7 @@ public:
 {
     _isTargetingInterfaceBuilder = NSProcessInfo.processInfo.mgl_isInterfaceBuilderDesignablesAgent;
     _opaque = NO;
+    _atLeastiOS_12_2_0 = [NSProcessInfo.processInfo isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){12,2,0}];
 
     BOOL background = [UIApplication sharedApplication].applicationState == UIApplicationStateBackground;
     if (!background)
@@ -1123,13 +1129,12 @@ public:
         [self updateUserLocationAnnotationView];
         [self updateAnnotationViews];
         [self updateCalloutView];
-        
+
 #ifdef MGL_RECREATE_GL_IN_AN_EMERGENCY
-#if (defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 120200)
         // See https://github.com/mapbox/mapbox-gl-native/issues/14232
         // glClear can be blocked for 1 second. This code is an "escape hatch",
         // an attempt to detect this situation and rebuild the GL views.
-        if (self.enablePresentsWithTransaction)
+        if (self.enablePresentsWithTransaction && _atLeastiOS_12_2_0)
         {
             CFTimeInterval before = CACurrentMediaTime();
             [self.glView display];
@@ -1143,7 +1148,6 @@ public:
         }
         else
 #endif
-#endif
         {
             [self.glView display];
         }