How to implement scale-9 (9-slice) for custom background art created for UIButton

Question

What do I need to do programatically in order to use the same background image for UIButton of variable size? (commonly known as 9-slice scaling or scale-9)

Answer 1

I know this is an old thread, but to anyone who stumbles upon this after iOS 5 is released, it should be noted from Apple's documentation that the stretchableImageWithLeftCapWidth:topCapHeight: method is deprecated as of iOS 5:

Deprecated UIImage Methods

Deprecated in iOS 5.0. Deprecated. Use the resizableImageWithCapInsets: instead, specifying cap insets such that the interior is a 1x1 area.

So now that iOS 6 has been announced and will be here soon, anyone developing for iOS 5 and higher should probably take a look at resizableImageWithCapInsets instead, which documentation can be found here:

UIImage Class Reference - resizableImageWithCapInsets

Just thought I'd mention it to help any developers who needed an updated answer to this problem.

Answer 2

Check out:

- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight

In the UIImage class.

If I understand what you're looking for correctly, this while allow you to use one png to define how your button looks, and it will stretch to any size vertically or horizontally.