如何在Swift中创建具有自定义形状的UIButton？

Question

I need to create button like this

and the change the background programmatically like this

and like this

I can not use images for different states of a button because each time I have different text on it.

What to start from ? I tried to understand CoreGraphics and CoreAnimation but there is too small amount of examples and tutorials so my attempts didn't give me any success.

Answer 1

You can , and should, use an image for this. UIKit has a method resizableImageWithCapInsets that creates resizable images. You feed it a minimum sized image and the system stretches it to fit the desired size. It looks like your image is fixed in height, which is good since you can't do smooth gradients with this technique.

Answer 2

UIButton s are composed of a background image and title text, so you can use an image for the background shapes ( setBackgroundImage(_:forState:) ), and then change the text using setTitle(_:forState:) .

However, you can still use Core Graphics for this, and there are benefits to doing so, such as the fact that it reduces the number of rendered assets in your app bundle. For this, probably the best approach is to create a CAShapeLayer with a path constructed from a UIBezierPath , and then render it into a graphics context. From this context, you can pull out a UIImage instance, and treat it just the same as an image loaded from a JPEG or PNG asset (that is, set it as the buttons background image using setBackgroundImage(_:forState:) ).