[ios] Disable implicit animation of user dot bounds

ref #1125

CHANGELOG.md

@@ -60,6 +60,7 @@ Known issues:
 - Updated documentation to reflect the requirement that you must embed the framework in the “Embedded Binaries” section in Xcode. ([#4011](https://github.com/mapbox/mapbox-gl-native/issues/4011))
 - Telemetry location gathering now only occurs when the device is in motion (https://github.com/mapbox/mapbox-gl-native/pull/4115)
 - Polygons and polylines now default to using the map view’s tint color. ([#4028](https://github.com/mapbox/mapbox-gl-native/pull/4028))
+- The user dot no longer lags when panning the map. ([#3683](https://github.com/mapbox/mapbox-gl-native/pull/3683))
 - The Improve This Map tool now uses the same zoom level that is currently being shown in the map view. ([#4068](https://github.com/mapbox/mapbox-gl-native/pull/4068))
 - Fixed a formatting issue in the documentation for `MGLCoordinateBoundsIsEmpty()`. ([#3958](https://github.com/mapbox/mapbox-gl-native/pull/3958))
 

platform/ios/src/MGLUserLocationAnnotationView.m

@@ -507,4 +507,14 @@ const CGFloat MGLUserLocationAnnotationArrowSize = MGLUserLocationAnnotationPuck
     return ovalPath;
 }
 
+- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event
+{
+    // Allow mbgl to drive animation of this view’s bounds.
+    if ([event isEqualToString:@"bounds"])
+    {
+        return [NSNull null];
+    }
+    return [super actionForLayer:layer forKey:event];
+}
+
 @end