The NinePatch image was introduced by Google for the Android. The key feature of the image format is defined stretchable areas so that the image could resize to fit content without degradation. Google has also created tools so that Ninepatch images can easily be created, and if you are developing on Android then you probably miss the lack of Ninepatch image support in the iOS SDK.
I’ve found a library that allows you to easily utilize NinePatch images within your iOS apps so you can take advantage of the usefulness of this image format, and more easily create crossplatform apps.
The library is from Tortuga22 and can be found on Github here:
They have also written a guide with more on the NinePatch image format and how to use the library here.
You may also want to read Google’s information on the NinePatch image format.
Looks like a very useful library.