Re: devil of a time with an NSImageView
Re: devil of a time with an NSImageView
- Subject: Re: devil of a time with an NSImageView
- From: Jonathan Hess <email@hidden>
- Date: Thu, 20 Aug 2009 12:21:05 -0700
c. A couple of weeks ago on this list, one of our Apple experts
(Luke, maybe, but I can't remember for sure) said to use the more
specialized method (such as 'windowDidLoad') *instead of* the
generic 'awakeFromNib', if the class has it.
I missed that thread. Do you happen to know some keywords from the
subject?
While I was looking for this thread, I found this old answer from an
other Cocoa expert (Chris Hanson):
http://lists.apple.com/archives/cocoa-dev/2003/Jul/msg00260.html
I'm quoting the conclusion:
“I prefer to use -awakeFromNib only to finish configuring controls
themselves, while I prefer to populate them in -windowDidLoad (or
its NSDocument equivalent). Why? Because they're conceptually two
different thing. The first is essentially to make up for a lack of
Interface Builder palettes to finish configuring your view objects
-- for instance, being able to set an NSTableView's double-click
action, or configuring a data cell for a table column -- while the
second involves gluing your model objects to your view objects."
Another reason to prefer a method like viewDidLoad, or windowDidLoad
to awakeFromNib is that awakeFromNib can potentially be called twice
on the same object. For example, if you have a window controller, and
that window controller loads its main NIB file, it will get an
awakeFromNib message. If that window controller later manually loads a
second nib file, to present a sheet for example, it will have
awakeFromNib sent to it a second time since it's the file's owner of
the NIB file. This second awakeFromNib invocation usually comes as a
surprise.
I recommend using awakeFromNib to do things like configure an object
that awakes from a nib, but doesn't care which particular NIB it is.
For example, if I had a MyView, and I represented it in nib files with
a "Custom View", and I want them all to start out with their enabled
boolean set to YES, I would implement awakeFromNib on MyView to set
the property to YES. Now, if one of my specific windows controllers
had a NIB with an instance of MyView in it, and it wanted that
instance to be initially disabled, I would configure that in the
window controller's windowDidLoad method.
Jon Hess
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