On Mar 29, 2011, at 4:25 PM, Matt Neuburg wrote:
> On Tue, 29 Mar 2011 11:20:31 -0700, Lou Zell <lzel...@gmail.com> said:
>> I have a subclass of UIButton, call it MyButton, that I would like to
>> function as a vanilla UIButton but also pass touch events to the next
>> responder (I'm interested in eventually getting the events in
>> UIViewController). I can do something like this in MyButton:
>>
>> -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
>> {
>> [[self nextResponder] touchesBegan:touches withEvent:event];
>> }
>
> Don't do that. The way to pass touches up the responder chain is by calling
> super. This will do exactly what you're after, I think.
>
> However, as already implied, you might be better off with a different
> architecture. It isn't at all clear why you'd do what you're describing. Let
> the button act as a button. If you need further information about what's
> going on, consider a gesture recognizer, perhaps, or just use the button's
> control events. In any case there should be no need to interfere at the very
> low level of the touches... responder methods. There are *many* ways to
> interfere with aspects of touch delivery; they are quite interesting, but be
> careful or you'll break something.
>
> m.
Moreover, according to the Event Handling Guide for iOS,
http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/MultitouchEvents/MultitouchEvents.html
"Important: If your custom responder class is a subclass of UIView or
UIViewController, you should implement all of the methods described in “The
Event-Handling Methods.” If your class is a subclass of any other UIKit
responder class, you do not need to override all of the event-handling methods;
however, in those methods that you do override, be sure to call the superclass
implementation of the method (for example, super touchesBegan:touches
withEvent:theEvent];). The reason for this guideline is simple: All views that
process touches, including your own, expect (or should expect) to receive a
full touch-event stream. If you prevent a UIKit responder object from receiving
touches for a certain phase of an event, the resulting behavior may be
undefined and probably undesirable."
and, further down,
"Handling Events in Subclasses of UIKit Views and Controls
If you subclass a view or control class of the UIKit framework (for example,
UIImageView or UISwitch) for the purpose of altering or extending
event-handling behavior, you should keep the following points in mind:
- Unlike in a custom view, it is not necessary to override each event-handling
method.
- Always invoke the superclass implementation of each event-handling method
that you do override.
- Do not forward events to UIKit framework objects."
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