-Removed casting to FlutterViewController(the casting led to a crash if my root view controller isn't FlutterViewController), all it needs is a UiViewController instance to present the activity controller
-Added modal presentation for activity controller
-Removed casting to FlutterViewController(the casting led to a crash if my root view controller isn't FlutterViewController), all it needs is a UiViewController instance to present the activity controller -Added modal presentation for activity controller
issue fix #73