QML Test with grabImage() fails on iOS

        function test_progresscircle_indeterminate(){
            var imgCompare1 = grabImage(obj);
            //do not use 1000 as it is the standard repeat interval for ProgressCircle
            wait(800);
            var imgCompare2 = grabImage(obj);
            verify(!imgCompare1.equals(imgCompare2), "TEST: ProgressCircle changed in indeterminate mode");
        }

        function test_set_image(){
            var noImage = grabImage(obj);
            obj.source = "qrc:/test_image.png";
            wait(1000);
            var testImg = grabImage(obj);
            verify(!noImage.equals(testImg), "TEST: Set image");
        }