Re: acceptsFirstResponder vrs canBecomeKeyView
Re: acceptsFirstResponder vrs canBecomeKeyView
- Subject: Re: acceptsFirstResponder vrs canBecomeKeyView
- From: "Ken Ferry" <email@hidden>
- Date: Fri, 23 Mar 2007 13:59:14 -0700
Hi Jesse,
The docs say that canBecomeKeyView will automatically return YES if acceptsFirstResponder is YES.
Where does it say that? That isn't correct. canBecomeKeyView should
imply acceptsFirstResponder, but not the other way around.
acceptsFirstResponder controls whether a responder will accept first
responder status if it is asked (i.e. -[NSWindow makeFirstResponder:]
is called with the responder). -[NSView canBecomeKeyView] controls
whether AppKit will ask a view to become responder in the first place.
The second calls acceptsFirstResponder, but also checks information
such as whether the view is hidden and whether full keyboard access is
on.
-[NSView canBecomeKeyView] is rarely overridden, -[NSResponder
acceptsFirstResponder] is frequently overridden.
Here's some example behavior with NSButton:
NSButton almost always returns YES to acceptsFirstResponder. It will
return NO if, say, the button is disabled. (NSButton doesn't override
acceptsFirstResponder, though. NSControl delegates to [[control cell]
acceptsFirstResponder], and NSButtonCell has the above behavior.)
NSButton will return NO from canBecomeKeyView if full keyboard access
is off, otherwise usually YES. It doesn't override the NSView level
canBecomeKeyView. No public class in AppKit does.
The acceptsFirstResponder implementation is usually pretty simple.
Hope that helps some!
Ken Ferry
Cocoa Frameworks
On 3/22/07, Jesse Grosjean <email@hidden> wrote:
I'm trying to understand the difference between acceptsFirstResponder
and canBecomeKeyView. The docs say that canBecomeKeyView will
automatically return YES if acceptsFirstResponder is YES. But are
there cases where acceptsFirstResponder would be NO and
canBecomeKeyView would be YES?
Can someone give some examples on how they differ and what
canBecomeKeyView is needed?
Thanks,
Jesse
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