[ios] Proper limiting behavior when trying to zoom out fully

- Bail from quick zoom if new zoom is same as old zoom
- Allow pinch gesture at minZoom to still move the map

2 files changed, 8 insertions, 9 deletions

diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 63e6a4d398..a8efb491dd 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -6,6 +6,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 
 * Reduced the size of the dynamic framework by optimizing symbol visibility. ([#7604](https://github.com/mapbox/mapbox-gl-native/pull/7604))
 * Fixed an issue where the attribution button would have its custom tint color reset when the map view received a tint color change notification, such as when an alert controller was presented. ([#9598](https://github.com/mapbox/mapbox-gl-native/pull/9598))
+* Improved the behavior of zoom gestures when the map reaches the minimum zoom limit. ([#9626](https://github.com/mapbox/mapbox-gl-native/pull/9626))
 * Bitcode symbol maps (.bcsymbolmap files) are now included with the dynamic framework. ([#9613](https://github.com/mapbox/mapbox-gl-native/pull/9613))
 
 ## 3.6.0 - June 29, 2017
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 2de1496998..3db0bc03b2 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -1280,8 +1280,6 @@ public:
 {
     if ( ! self.isZoomEnabled) return;
 
-    if (_mbglMap->getZoom() <= _mbglMap->getMinZoom() && pinch.scale < 1) return;
-
     _mbglMap->cancelTransitions();
 
     CGPoint centerPoint = [self anchorPointForGesture:pinch];
@@ -1297,17 +1295,17 @@ public:
     }
     else if (pinch.state == UIGestureRecognizerStateChanged)
     {
+        // Zoom limiting happens at the core level.
         CGFloat newScale = self.scale * pinch.scale;
-        double zoom = log2(newScale);
-        if (zoom < _mbglMap->getMinZoom()) return;
-        
+        double newZoom = log2(newScale);
+
         // Calculates the final camera zoom, has no effect within current map camera.
-        MGLMapCamera *toCamera = [self cameraByZoomingToZoomLevel:zoom aroundAnchorPoint:centerPoint];
+        MGLMapCamera *toCamera = [self cameraByZoomingToZoomLevel:newZoom aroundAnchorPoint:centerPoint];
         
         if (![self.delegate respondsToSelector:@selector(mapView:shouldChangeFromCamera:toCamera:)] ||
             [self.delegate mapView:self shouldChangeFromCamera:oldCamera toCamera:toCamera])
         {
-            _mbglMap->setZoom(zoom, mbgl::ScreenCoordinate { centerPoint.x, centerPoint.y });
+            _mbglMap->setZoom(newZoom, mbgl::ScreenCoordinate { centerPoint.x, centerPoint.y });
             // The gesture recognizer only reports the gesture’s current center
             // point, so use the previous center point to anchor the transition.
             // If the number of touches has changed, the remembered center point is
@@ -1655,9 +1653,9 @@ public:
     {
         CGFloat distance = [quickZoom locationInView:quickZoom.view].y - self.quickZoomStart;
 
-        CGFloat newZoom = log2f(self.scale) + (distance / 75);
+        CGFloat newZoom = MAX(log2f(self.scale) + (distance / 75), _mbglMap->getMinZoom());
 
-        if (newZoom < _mbglMap->getMinZoom()) return;
+        if (_mbglMap->getZoom() == newZoom) return;
 
         CGPoint centerPoint = [self anchorPointForGesture:quickZoom];