Sebastian Rehnby has published SBRXCallbackURLKit on Github. SBRXCallbackURLKit is a “simple library that makes it easy to add x-callback-url support to your app.”
SBRXCallbackURLKit has a block-based API for declaring URL handlers and Cocoapods support for easy integration. Worth a look if you are getting started on URL scheme integration in an app. You might also want to look at Inter-app Communication, which works in a similar fashion, and see which best suits your needs.