Static Library

Compiling Image Resources into a Static Library

I’ve recently been working on a static library for distribution to other developers — Audiobus — and I need to include a couple of graphical resources with the distribution. The usual solution to this is to include the resources separately in a bundle, and require the user to drop them in to their project along with the static library.

I thought I’d see if I could make the process just a little neater, and successfully devised a way to compile the images straight into the library, so the distribution remains nice and clean — just the library itself and a few header files.

Now, I can pop image resources into a folder, and after compiling, access them within the static library with:

UIImage *image = TPGetCompiledImage(@"Button.png");

It automatically handles “@2x” Retina images (although it doesn’t currently do “~ipad” versions).

Here’s how it’s done.

The magic is in a shell script which uses the xxd hex dump tool to create C code that represents the image data as a byte array, then creates around it a set of utilities to turn those arrays into UIImages on demand.

Along with it is a couple of template files — a header and implementation file — that describe the format of the derived code.

Finally, a little tweaking of the project in Xcode (with a brief foray into a text editor to work around some Xcode shortcomings) puts it all together.