Intercepting and Forwarding Touch Events
The key to this overlay lies in intercepting touch events, creating a floating presentation above your normal interface, and then forwarding those events on to your application. A TOUCHkit view lies on top of your interface. The custom window class grabs user touch events and presents them as circles in the TOUCHkit view. It then forwards them as if the user were interacting with a normal UIWindow. To accomplish this, this recipe uses event forwarding.
Event forwarding is achieved by calling a secondary event handler. The TOUCHOverlayWindow class overrides UIWindow’s sendEvent: method to force touch drawing and then invokes its superclass implementation to return control to the normal responder chain. ...
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