When set to NO, user events—such as touch and keyboard—intended for the view are ignored and removed from the event queue. When set to YES, events are delivered to the view normally. The default value of this property is YES.
During an animation, user interactions are temporarily disabled for all views involved in the animation, regardless of the value in this property. You can disable this behavior by specifying the UIViewAnimationOptionAllowUserInteraction option when configuring the animation.
Note: Some UIKit subclasses override this property and return a different default value. See the documentation for that class to determine if it returns a different value.