Question

I’m trying to observe changes to an NSMutableString isDetailView:

-(void)viewDidLoad {
    [self addObserver:self forKeyPath:@"isDetailView" options:NSKeyValueObservingOptionNew context:nil];
    [isDetailView setString:@"YES"];
}


- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSLog(@"obersedValueFOrKeyPath:%@", keyPath);
}

But the observeValueForKeyPath method never gets called. Any ideas?

Answer 1

You are not changing the property, only the content of the object it points to. If you make isDetailView a normal string and do

[self setIsDetailView: @"YES"]

it will work.

By the way, properties that start “is” are conventionally supposed to be boolean and that looks like a more appropriate type in this case too.