iOS Components and Frameworks: Understanding the Advanced Features of the iOS SDK

Collisions

In the preceding section gravity was covered; however, the object that the gravity was applied to fell through the bottom of the screen and continued on its way into infinity. This is because no collision points were defined and the object had nothing to stop its descent.

The previous example will be modified to add collision boundaries to the enclosing view, as well as adding a secondary image object. The collision example begins the same way as gravity; however, two image views are now used.

Creating a UICollisionBehavior object is very similar to creating a UIGravityBehavior object. The object is initialized with the UIViews that should be affected, in this case two UIImageViews. In addition to the views, collision behavior also ...