两种方法删除NSUserDefaults所有记录

//方法一
NSString *appDomain = [[ NSBundle mainBundle ] bundleIdentifier ];
[[ NSUserDefaults standardUserDefaults ] removePersistentDomainForName :appDomain];

//方法二
- ( void )resetDefaults {
    NSUserDefaults * defs = [ NSUserDefaults standardUserDefaults ];
    NSDictionary * dict = [defs dictionaryRepresentation ];
    for ( id key in dict) {
        [defs removeObjectForKey :key];
    }
    [defs synchronize ];

}