Textured resizable buttons with Core Image filter and appearance proxy iOS

Question

The app I'm writing involves buttons that have a slight noise filter texture, which can be any size. For a standard button I'd simply use resizableImageWithCapInsets: but due to the texture, this causes unusual artefacts to appear on the resulting button.

A solution I have in mind, is to use the Core Image monochrome filter combined with the random noise filter to add the noise texture to a plain image. In theory this works, and in practice this has been shown to work (One example here) but these are all in cases where the button size is known at the point of invoking the CI code.

What I'm looking to do, is use the appearance proxies, so across the app I can simply set the style of UIBarButtonItems for instance.

Is there a way I can apply these CI filters to the buttons through the appearance proxies or isn't this possible? Would something like a category on UIImage to add noise work? I'm not entirely sure at which point the appearance proxy would actually invoke that code.

Any help is appreciated

Answer 1

OK So I finally solved it but found out some stuff on the way.

It seems you can create a category on UIImage and use that in the appearance proxy. I created a category to add noise, and it seemed to partly work, but I couldn't get it looking how I wanted as it wasn't quite rendering properly, but in the process of coding this discovered another method

resizableImageWithCapInsets:resizingMode:

Because the texture I was dealing with was simply noise, it could be tiled, so rather than the image now being stretched, the centre of the image is instead tiled which gives me the appearance I needed :)