清除 NSUserDefaults
迅速
let bundleIdentifier = NSBundle.mainBundle().bundleIdentifier()
NSUserDefaults.standardUserDefaults().removePersistentDomainForName(bundleIdentifier)
Objective-C
NSString *bundleIdentifier = [[NSBundle mainBundle] bundleIdentifier];
[[NSUserDefaults standardUserDefaults] removePersistentDomainForName: bundleIdentifier];