UIButton中的imageview属性和-（void）setImage：forState：有什么区别？

Question

I just tried to set a new image (UIImage object) for my UIButton using myBtn.imageview.image = newimg; then I found it didn't work.

After that I get the correct solution that using setImage:forState: , the documentation about UIButton says "imageView is the button's image view. (read-only)"

How should I get it? What's the difference?

Thanks!

Answer 1

As the documentation says( "imageView is the button's image view. (read-only)" ), it is a read only property and you cant just change the imageView . You have to use the recommended method setImage:forState: . Basically UIButton might be having a different implementation than what you are expecting and myBtn.imageview.image may not actually set the desired image to the button. setImage:forState: might be having an implementation which could be completely different from just setting myBtn.imageview.image = newimg; . By directly setting like in your question, you might get some unexpected results since the actual implementation is not executed.