I'm trying to understand a bit more about the Responder chain,
especially how it relates to regular (non-document) applications using
NSView and NSViewController added into the View Hierarchy.
Katidev.com has a nice series of articles on the related issue for
Document based applications. (It starts at http://katidev.com/blog/2008/04/09/nsviewcontroller-the-new-c-in-mvc-pt-1-of-3/)
However, it doesnt give me enough background to understand why I need
a XSViewController (extension of NSViewController), and how the
Controller hierarchy fits in with the View Hierarchy.
When does an application following the Responder Chain look at the
ViewController?
The clues I have (from KatiDev and Apple's "Cocoa Event-Handling
Guide" (aka EventOverview.pdf) is that the EVENT chain starts with the
current focus Window's First Responder, and then it traverses the View
Hierarchy's responder chain.... which I think means going up to the
parent (containing) view and checking its responder until you get to
the Window, then the WindowDelegate, and then the NSWindowController.
Event Messages (aka events) dont get passed to the NSViewController in
the normal (NS) world. The XSController extension (katidev.com) puts
these back in, such that it when the event gets to the
XSWindowController it would get passed down the XS-responder chain
(see the article).
Action Messages (actions) follow a slightly different path. Actions
start by an Event responder (eg a ButtonCell) firing off a
sendAction:to:from. If there is a designated Target (to:) defined by
the responder, that object gets the action. Otherwise the
sendAction:to:from goes to the First Responder, up the view hierarchy,
to the NSWindow, to the WindowDelegate, to the NSApp then the
AppDelegate.
Again, the NSViewController doesnt appear in the responder chain,
unless it was designated by the initial Event Responder. If it was
designated, but doesnt respond, what happens? An Error or does it go
back to the responder chain?
The NSViewController is a Responder, but the associated view does not
patch it into the responder chain for either event or action responding.
Correct?
But if my design explicitly specifies the target (connecting IBActions
in InterfaceBuilder), I dont have to worry about the Responder chain
for actions. Correct?
Thanks
Jerry Isdale
[EMAIL PROTECTED]
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