Re: Responder Chain Confusion
Re: Responder Chain Confusion
- Subject: Re: Responder Chain Confusion
- From: Kyle Sluder <email@hidden>
- Date: Sun, 07 Sep 2014 11:16:02 -0700
On Sep 7, 2014, at 9:24 AM, email@hidden wrote:
>
> Hi all
>
> I just spent a bit of time poking around the responder chain and nil targeted actions.
> I built a view controller and a view hierarchy with controls that should be configurable.
> When instantiating the view controller the interface allows configuring the action SEL of the controls. Reuse is the goal of course.
> I know 10.10 changes things greatly for view controllers. But on 10.9 that's not there.
>
> Anyway, I need to insert the view controller into the responder chain between its top level view and that view's superview.
> That wasn't too bad. Implement the missing reference to the vc in a view subclass and give the vc a callback when the view is in place.
>
> But what I found while tinkering is that for non-document based apps from a vanilla project template there was no next responder for the window or the NSApplication instance.
> I had a method in the app delegate that I was trying to reach via nil targeted action. It couldn't get there.
> So I set the window nextResponder to the app and the app to the app delegate. I also made the app delegate an NSResponder subclass.
>
> It feels like overkill.
> Am I missing something simple?
IIRC, the window is not supposed to have a nextResponder. Conceptually, the next responder of a window is its delegate, and the next responder of an application is *its* delegate, but there is no requirement that these objects are instances of subclasses of NSResponder. Therefore the responder chain mechanism manually jumps from the window to its delegate, then to the application, and finally to the app’s delegate. (It also inserts window controllers as well as the shared NSDocumentController instance if one has been created.)
If the message never reached your app delegate, I suspect you failed to patch the view controller’s nextResponder in correctly.
--Kyle Sluder
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