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UDID UDP, and unreliable transmission UI classes UI elements, main classes of UIAcceleration and gravity parsing UIAccelerometer UIAccelerometerDelegate UIActionSheet UIActivityIndicatorView UIAlertView UIApplication, 2nd and unhandled events beginIgnoringInteractionEvents endIgnoringInteractionEvents event regulation isIgnoringInteractionEvents sendAction:to:fromSender:forEvent: sharedApplication UIApplicationDelegate protocol UIApplicationMain UIBarButtonItem and UINavigationItem modifying look UIButton, 2nd, 3rd UIColor, 2nd, 3rd and cell label UIControl, 2nd accepting user input event-handling infrastructure events properties specifying which method should run after an event UIControlEventAllEditingEvents UIControlEventAllEvents ...