Let's say you're writing an iOS app where you need to transition from scene one to scene two and pass along some context. When iOS 5 came along, storyboards made this simple. You just create a segue from scene one to scene two, and set one or more properties in the segue's destination view controller in scene one's implementation of prepareForSegue:sender: . The scene one view controller imports the header file for scene two's view controller so it's easy for scene one to pass information along to scene two.
Full article: http://pragmaticstudio.com/blog/2013/2/5/unwind-segues