Re: Substituting instance of cell subclass for instance of superclass
Re: Substituting instance of cell subclass for instance of superclass
- Subject: Re: Substituting instance of cell subclass for instance of superclass
- From: James Walker <email@hidden>
- Date: Tue, 15 Nov 2016 12:46:30 -0800
On 11/11/2016 6:27 PM, Kyle Sluder wrote:
On Fri, Nov 11, 2016, at 07:34 PM, James Walker wrote:
I want to replace (for example) an instance of NSButtonCell with an
instance of my own subclass of NSButtonCell on the fly. Now, I know
that's not a common thing to want to do; normally, you'd edit the nib to
use whatever cell class you want. But I'd like to be able to do it to
an NSAlert, for which I don't have a nib.
You also have no idea if the NSAlert is already using a custom
NSButtonCell subclass—or whether it uses NSControl at all.
I can certainly check at runtime, using [view isMemberOfClass: [NSButton
class]] and likewise for the cell. If things aren't what I expect, I
just won't change the window, which won't be the end of the world.
Your only option here is to reimplement the alert.
--Kyle Sluder
So, my thought was to first make an instance of my cell class that
copies all the state of the NSButtonCell instance, and then use
-[NSControl setCell:]. The documentation on setCell: does say:
"Use this method with great care as it can irrevocably damage the
affected control; specifically, you should only use this method in
initializers for subclasses of NSControl."
Anyone know what kind of damage we're talking about?
Anyway, as far as copying the cell state, I tried this:
- (id) initCopyingBaseCell: (NSButtonCell*) oldCell
{
NSData* archive = [NSKeyedArchiver
archivedDataWithRootObject: oldCell];
NSKeyedUnarchiver* coder = [[[NSKeyedUnarchiver alloc]
initForReadingWithData: archive] autorelease];
self = [super initWithCoder: coder];
if (self != nil)
{
}
return self;
}
However, the new cell has failed to copy much of the state of the old
one. Things like title, font, target, action, bezelStyle... I can
manually copy anything that I notice is missing, but I'm just wondering
why the keyed archiver approach here doesn't work.
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