Are you excited about extensions in iOS 8? Want to learn how to build an extension for your own iOS app? Then join us in this simple tutorial that will get you up to speed on Action extensions. We'll build a simple app and extension from scratch, and walk you through the whole process so you can start experimenting with your own ideas.
Source files for the Tuts+ tutorial: iOS 8: How to Build a Simple Action Extension
Read this tutorial on Tuts+