Question

I’m trying to observe a string in a Singleton from a view controller.

In my view controller I do this in viewDidLoad:

  Singleton *singleton = [Singleton sharedSingleton];
    [singleton addObserver:self
                    forKeyPath:@"testString"
                       options:NSKeyValueObservingOptionNew
                       context:nil];

..and this code is at the bottom of the view controller:

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

The testString, in the Singleton, is changed 5 seconds later, but the observeValueForKeyPath is not called.. What have I done wrong?

Answer 1

Use properties e.g. self.testString = newString instead of testString = newString or KVO will not work.