Merge pull request #1854 from mapbox/1ec5-symbol-exception-1851

fixes #1851: assert if -mapView:symbolNameForAnnotation: is implemented

include/mbgl/ios/MGLMapView.h

@@ -345,10 +345,6 @@ IB_DESIGNABLE
 
 /** @name Managing the Display of Annotations */
 
-/** Returns the style's symbol name to use for the marker for the specified point annotation object.
-*   @param mapView The map view that requested the annotation symbol name.
-*   @param annotation The object representing the annotation that is about to be displayed. 
-*   @return The marker symbol to display for the specified annotation or `nil` if you want to display the default symbol. */
 - (nullable NSString *)mapView:(MGLMapView *)mapView symbolNameForAnnotation:(id <MGLAnnotation>)annotation __attribute__((unavailable("Use -mapView:imageForAnnotation:.")));
 
 /** Returns an image object to use for the marker for the specified point annotation object.

platform/ios/MGLMapView.mm

@@ -455,6 +455,14 @@ std::chrono::steady_clock::duration secondsAsDuration(float duration)
     if (_delegate == delegate) return;
 
     _delegate = delegate;
+    
+    if ([delegate respondsToSelector:@selector(mapView:symbolNameForAnnotation:)])
+    {
+        [NSException raise:@"Method unavailable" format:
+         @"-mapView:symbolNameForAnnotation: has been removed from the MGLMapViewDelegate protocol, but %@ still implements it. "
+         @"Implement -[%@ mapView:imageForAnnotation:] instead.",
+         NSStringFromClass([delegate class]), NSStringFromClass([delegate class])];
+    }
 }
 
 #pragma mark - Layout -