How to convert UIView to UIImage without background?

I have UIView that contain a pin image and a label, as we know UIView is rectangle so if I convert UIView to UIImage,UIImage is also rectangle, I want make UIImage like the a pin image because if user click a background, UIImage's event will be called too.. I want to convert UIView to UIImage without it's background, how can it be?

I use this method to change UIView to UIImage

-(UIImage *) ChangeViewToImage : (UIView *) view{

UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
  UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return img;
}

Hmm.. example like this, I have a rectangle as a UIView and a triangle as a shape in UIView. and then I want to make this UIView become a UIImage, but I just want the triangle without background, so the image just a triangle.. how can I do It?