With the introduction of iOS 7, Apple completely removed the skeuomorphic design that has been used since the introduction of the iPhone and iOS. In its place is a new and refreshing flat design that features muted gradients and minimal interface elements. Apple has strongly encouraged developers to move away from a skeuomorphic and real-world-based design in favor of these flat designs.
Although we are guided away from a real-world look, Apple also strongly encourages that your user interface have a real-world feel. Some may think this is a contradiction; however, the goal is to give users a deeper connection to the user interface. UI elements that respond to touch, gestures, and changes in orientation are examples of how to apply this new design paradigm. In order to help assist in this new design approach, Apple has introduced two very nifty APIs, UIKit Dynamics and Motion Effects.