fA UIEvent object (or, simply, an event object) represents an event in iOS. There are three general types of event: touch events, motion events, and remote-control events. It is declared in UIKit framework. It is available in iOS 2.0 and later
A UIEvent object representing a touch event is persistent throughout a multi-touch sequence. UIKit reuses the same UIEvent instance for every event delivered to the application.
You can obtain event types and subtypes from the type and subtype properties. UIEvent defines event types for touch, motion, and remote-control events. It also defines a motion subtype for "shake” events and a series of subtype constants for remote-control events, such as “play” and “previous track.” The first responder or any responder in the responder chain implements the motion-related methods of UIResponder (such as motionBegan:withEvent:) to handle shaking-motion events. To handle remote-control events, a responder object must implement the remoteControlReceivedWithEvent: method of UIResponder.
The touchesForGestureRecognizer: method, which was introduced in iOS 3.2, allows you to query a gesture-recognizer object (an instance of a subclass of UIGestureRecognizer) for the touches it is currently handling.
Source: UIEvent Class Reference
Related SO questions:
UIGestureRecognizer receive touch but forward it to UIControl as well
