One of my viewcontrollers uses the representedObject to bind to the
NSArrayController that holds all the data for the application (OS X, ARC on). I
declared a local property mySelection (an NSArray) and bind it to the
representedObject as follows:
[self bind:@"mySelection" toObject:self.representedObject
withKeyPath:@"selectedObjects" options:nil];
So far so good.
Now when the user changes mySelection, not only my local property needs to be
updated, but also some other parts in my code. So I cannot just rely on the
automatically generated setter, and thus need to monitor a change in
mySelection. After some searching I came up with the following:
[self.representedObject addObserver:self forKeyPath:@"selectedObjects"
options:NSKeyValueObservingOptionNew context: nil];
and then:
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
change:(NSDictionary *)change context:(void *)context
{
if ([keyPath isEqualToString: @"selectedObjects"])
{
// do additional stuff
}
else
{
[super observeValueForKeyPath:keyPath ofObject:object change:change
context:context];
}
}
Again, this all works. Whenever the user changes the selection,
observeValueForKeyPath: gets called and the "do additional stuff" gets executed.
But I have the feeling I am over-complicating things. From reading on this
subject I get the impression the approach above seems to be more for monitoring
properties in other classes, not in the owner class.
So, is this the correct way to do this (responding to a change in a local
property, or am I overlooking something very obvious?
Thanks,
- Koen.
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