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Understanding UIResponder by Dirk Smith

Understanding UIResponder by Dirk Smith

Dirk discusses UIResponder at CocoaHeads Durham in July 2012

Triangle Cocoa

July 28, 2012

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  1. Understanding UIResponder

  2. What is UIResponder? ✤ Basis of many regularly used components:

    UIView, UIViewController, AppDelegate, UIWindow ✤ Important for interacting with the application
  3. UIResponder Core Methods ✤ touchesBegan:withEvent: ✤ touchesMoved:withEvent: ✤ touchesEnded:withEvent: ✤

    touchesCancelled:withEvent: ✤ becomeFirstResponder ✤ canBecomeFirstResponder ✤ canResignFirstResponder ✤ isFirstResponder
  4. UIResponder - First Responder ✤ An object can only become

    a first responder if the existing first responder returns TRUE for canResignFirstResponder and the current object returns TRUE for canBecomeFirstResponder ✤ The default for canResignFirstResponder is TRUE and FALSE for canBecomeFirstResponder ✤ InputView is shown when UIResponder becomes FirstResponder (like a keyboard)
  5. UIResponder Chain

  6. UIResponder Chain ✤ nextResponder defaults to nil; subclasses are responsible

    for determining the next object in the chain ✤ UIView returns its ViewController if its managed by one, or its superview if not ✤ UIViewController returns the UIWindow ✤ UIWindow returns the AppDelegate ✤ Event will be thrown out if not handled
  7. Questions? Magnets, how do they work?

  8. Thanks! My name is Dirk @dirkthedaring dirk@twotoasters.com