Gratuity (iOS App) Settings Transition

Hey everyone, I'm new here. I'm a UX designer by trade which doesn't let to a lot of dribbble type work. Recently, I have been teaching myself Objective C, Swift, and iOS Development. I've decided to post some of the designs I've come up with. The key to my shots is that these are all real and in code and work on an actual device.

For this effect I used the new UIPresentationController introduced in iOS8. The video is cropped and slowed down a bit for this GIF. The subtle springy animation and the subtle zoom out of the old ViewController and the new ViewController are really satisfying on the device. The GIF really doesn't do it justice. A full video is here: http://www.jeffburg.com/zzNotPortfolio/dribbble/gratuity-settings-transition.mov Also, its on the App Store: https://itunes.apple.com/us/app/gratuity-simple-tip-calculator/id933679671?mt=8