[ios] fix #6361: source query nullability & return nil for unfound results (#6408)

Also removes some dead code in MGLStyle.mm.

2 files changed, 5 insertions, 11 deletions

diff --git a/platform/darwin/src/MGLStyle.h b/platform/darwin/src/MGLStyle.h
index bc4c32da91..585d15c08c 100644
--- a/platform/darwin/src/MGLStyle.h
+++ b/platform/darwin/src/MGLStyle.h
@@ -187,7 +187,7 @@ static const NSInteger MGLStyleDefaultVersion = 9;
  
  @return source An instance of an `MGLSource` subclass.
  */
-- (MGLSource *)sourceWithIdentifier:(NSString *)identifier;
+- (nullable MGLSource *)sourceWithIdentifier:(NSString *)identifier;
 
 /**
  Adds a new layer on top of existing layers.
diff --git a/platform/darwin/src/MGLStyle.mm b/platform/darwin/src/MGLStyle.mm
index c785ef7b62..79d7d7e0f6 100644
--- a/platform/darwin/src/MGLStyle.mm
+++ b/platform/darwin/src/MGLStyle.mm
@@ -92,19 +92,11 @@ static NSURL *MGLStyleURL_emerald;
     return @(self.mapView.mbglMap->getStyleName().c_str());
 }
 
-- (mbgl::style::Layer *)mbglLayerWithIdentifier:(NSString *)identifier
-{
-    return self.mapView.mbglMap->getLayer(identifier.UTF8String);
-}
-
-- (mbgl::style::Source *)mbglSourceWithIdentifier:(NSString *)identifier
-{
-    return self.mapView.mbglMap->getSource(identifier.UTF8String);
-}
-
 - (id <MGLStyleLayer>)layerWithIdentifier:(NSString *)identifier
 {
     auto layer = self.mapView.mbglMap->getLayer(identifier.UTF8String);
+
+    if (!layer) return nil;
     
     Class clazz = [self classFromLayer:layer];
     
@@ -119,6 +111,8 @@ static NSURL *MGLStyleURL_emerald;
 - (MGLSource *)sourceWithIdentifier:(NSString *)identifier
 {
     auto s = self.mapView.mbglMap->getSource(identifier.UTF8String);
+
+    if (!s) return nil;
     
     Class clazz = [self classFromSource:s];