fixes #2044: add -showAnnotations:animated:

include/mbgl/ios/MGLMapView.h

@@ -151,6 +151,13 @@ IB_DESIGNABLE
 *   @param animated Specify `YES` to animate the change by smoothly scrolling and zooming or `NO` to immediately display the given bounds. */
 - (void)setVisibleCoordinates:(CLLocationCoordinate2D *)coordinates count:(NSUInteger)count edgePadding:(UIEdgeInsets)insets animated:(BOOL)animated;
 
+/** Sets the visible region so that the map displays the specified annotations.
+*
+*   Calling this method updates the value in the visibleCoordinateBounds property and potentially other properties to reflect the new map region.
+*   @param annotations The annotations that you want to be visible in the map.
+*   @param animated `YES` if you want the map region change to be animated, or `NO` if you want the map to display the new region immediately without animations. */
+- (void)showAnnotations:(NS_ARRAY_OF(id <MGLAnnotation>) *)annotations animated:(BOOL)animated;
+
 /** The heading of the map (measured in degrees) relative to true north. 
 *
 *   The value `0` means that the top edge of the map view corresponds to true north. The value `90` means the top of the map is pointing due east. The value `180` means the top of the map points due south, and so on. */

platform/ios/MGLMapView.mm

@@ -2151,6 +2151,29 @@ CLLocationCoordinate2D MGLLocationCoordinate2DFromLatLng(mbgl::LatLng latLng)
     }
 }
 
+- (void)showAnnotations:(NS_ARRAY_OF(id <MGLAnnotation>) *)annotations animated:(BOOL)animated
+{
+    if ( ! annotations || ! annotations.count) return;
+
+    mbgl::LatLngBounds bounds;
+
+    for (id <MGLAnnotation> annotation in annotations)
+    {
+        if ([annotation conformsToProtocol:@protocol(MGLOverlay)])
+        {
+            bounds.extend(MGLLatLngBoundsFromCoordinateBounds(((id <MGLOverlay>)annotation).overlayBounds));
+        }
+        else
+        {
+            bounds.extend(MGLLatLngFromLocationCoordinate2D(annotation.coordinate));
+        }
+    }
+
+    [self setVisibleCoordinateBounds:MGLCoordinateBoundsFromLatLngBounds(bounds)
+                         edgePadding:UIEdgeInsetsMake(100, 100, 100, 100)
+                            animated:animated];
+}
+
 #pragma mark - User Location -
 
 - (void)setShowsUserLocation:(BOOL)showsUserLocation