How to receive NSUserDefaultsDidChangeNotification iphone

Question

After a lot of searching I was not able to find whether you need to pass a dictionary object to:

[NSUserDefaultsDidChangeNotification addObserver: forKeyPath: options: context:]; 

and what should be provided in options if I want to be notified for even a single change in the userDefaults. Also what is keypath?

Answer 1

NSUserDefaultsDidChangeNotification is just a notification that is sent out when the defaults are changed. To listen out for it you need this code :

    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];     [center addObserver:self                selector:@selector(defaultsChanged:)                      name:NSUserDefaultsDidChangeNotification                  object:nil]; 

This will call the method defaultsChanged: when the notification is fired. You need to implement this method like this :

- (void)defaultsChanged:(NSNotification *)notification {     // Get the user defaults     NSUserDefaults *defaults = (NSUserDefaults *)[notification object];      // Do something with it     NSLog(@"%@", [defaults objectForKey:@"nameOfThingIAmInterestedIn"]); }