如何在没有背景的情况下将UIView转换为UIImage？

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 have UIView that contain a pin image and a la