Cocoa: How to bind a boolean property to NSCellStateValue?
cocoa, cocoa-bindings, nstextfield, nsvaluetransformer, state
Solution
`NSButton` isn't KVO compliant for the key `state`. Cocoa Bindings require the observed object to emit notifications when the observed property changes. As `NSButton`'s `state` is just a wrapper for its cell's `state`, `-[NSButton setState:]` method (and the automatic KVO notifications) isn't invoked when the user click the button (but `-[NSCell setState:]` is). If you set the model key path to `self.anonymousLoginCheckbox.cell.state`, it will work.
Problem
I would like to bind the boolean `enabled` property of an `NSTextField` to the state of an `NSButton`. I already tried adding a custom `NSValueTransformer` that transforms the state of the `NSButton` into `NSNumber`. However, in that scenario the text fields are disabled all the time for some reason. My second approach: To bad fails also since `NSValueTransformer` does not offer return primitives types such as `BOOL`. Example: The screenshot shows an example in which the text fields are disabled because the checkbox has the state `NSOnState`. I also would like to bind the labels to this state. Further, it would be convenient, if I could set a "disabled text" in Interface Builder. In the above example I set the text in the associated class. Edit: I set `self.anonymousLoginCheckbox.state` as the Model Key Path for the enabled property of the account text field. Similar for the password text field. However, it does not work. Update: I created an example project available on GitHub showing the implementation kindly described by Nicolas Bachschmidt.