In vc1 im setting a BOOL [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"myKey"];
In vc2 I want to observe if this BOOl changes [[NSUserDefaults standardUserDefaults] boolForKey:@"myKey"]
Checked here Add Observer to BOOL variable and Registering a bool for a NSNotification
neither seemed to fit my pattern
Use below code it will call when your BOOL value changed.You can use KVO to observe the value of your myKey .Write this in any class where you observe the values.Write it in viewDidLoad in vc2
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults addObserver:self
forKeyPath:@"myKey"
options:NSKeyValueObservingOptionNew
context:NULL];
Implement this method in your class where you have added observer in vc2
-(void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
//check here if it is myKey than do something
if([keyPath isEqualToString:@"myKey"]){
//do your work
NSLog(@"KVO: %@ changed property %@ to value %@", object, keyPath, change);
BOOL newValue = [[change objectForKey: NSKeyValueChangeNewKey] boolValue];
}
else{
NSLog(@"Not my key");
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
Remove observer in vc2 dealloc
-(void)dealloc{
[[NSUserDefaults standardUserDefaults] removeObserver:self forKeyPath:@"myKey"];
}
In observeValueForKeyPath check for if value changed for myKey than do whatever you want to.
Register for the NSUserDefaultsDidChangeNotification and check your user defaults whenever the notification fires to see if the value that changed is the one you're interested in.
