On May 18, 2008, at 8:36 PM, Jens Alfke wrote:
I've started playing with NSCollectionView and everything worked out beautifully (custom views, selection state handling for items etc.). One thing I can't figure out is how my application/document gets notified about a change of selection.If you bind the collection view to an NSArrayController, you can observe the controller's selection-related properties, either programmatically or by using bindings in IB. For example, you can bind a button's "enabled" property to the controller's "canRemove", to enable the button only when there's a selection.
Up until now I've tried to stay away from manual KVO, the complexity of things is overwhelming as it is. However, I have to say it's rather elegant and works perfectly for this case. Just to be sure I did things right, this is what I came up with:
@implementation MyCollectionViewController
- (void)dealloc
{
[arrayController removeObserver:self
forKeyPath:@"selectedObjects"];
[super dealloc];
}
-(void)awakeFromNib
{
[arrayController addObserver:self forKeyPath:@"selectedObjects"
options:NSKeyValueObservingOptionNew
context:nil];
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
// do whatever necessary here
}
Does this look OK, especially, is removeObserver: in dealloc: not too
late?
Thanks for you help! Regards Markus -- __________________________________________ Markus Spoettl
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