On Jan 3, 2011, at 9:27 AM, Richard Somers wrote:
I would like to establish bindings in Interface Builder between the
"objects" created by the custom view and some standard Interface
Builder widgets. The problem is 'awakeFromNib' is called AFTER the
bindings are established so the bindings never work.
On Jan 3, 2011, at 1:32 PM, Quincey Morris wrote:
If I understand your description correctly, you actually have a bug
in your code. At the time 'awakeFromNib' is called, bindings (and
therefore KVO observations) already exist on certain properties of
your custom view (that is, on the key-paths that represent those
properties) -- even though the property values are still nil, though
that's not inherently a problem.
My original problem consisted of several problems combined. The most
obscure one was related to KVO observations as suggested by Quincey.
I was trying to bind a NSTextField value property to CALayer subclass
property in Interface Builder. But changes in the model were not
reflected in the user interface. This is because "CALayer’s
implementation of automaticallyNotifiesObserversForKey: in 10.5
returns NO for all keys. In 10.6 it works as expected, returning only
NO for its own properties."
http://rhult.github.com/kvo-problems-with-calayer.html
Debugging bindings can be a challenge. In retrospect Apple provided
guidance for troubleshooting this specific issue. The 'Troubleshooting
Cocoa Bindings' section of 'Cocoa Bindings Programming Topics' states
"If changes made to a model value programmatically are not being
reflected in the user interface ... You should ensure that: The model
class has automatic key-value observing enabled or implements manual
key-value observing for the property."
--Richard Somers
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