NSUserDefaults not persisting

NSUserDefaults not persisting

I am using this tutorial to save settings and preferences using
NSUserDefault, but the settings do not persist when I close the
application and restart. What should I do?
Code:
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if(defaults) {
[defaults setObject: @"NO" forKey: @"enableGetStarted"];
[defaults setObject: [json mutableCopy] forKey: @"user"];
[defaults synchronize];
}
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
BOOL enabled = [defaults boolForKey:@"enableGetStarted"];
if([defaults dictionaryForKey: @"user"] != nil) {
NSMutableDictionary * user = [[defaults dictionaryForKey: @"user"]
mutableCopy];
[[API sharedInstance] setUser: user];
}
if([[API sharedInstance] isAuthorized]) {
[self fetchUser];
}