NSUserDefaults 

簡介：NSUserDefaults用來儲存資料量小的資料。支援：NSString/NSData/NSArray/NSNumber/NSDictionary

使用：

//建立
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
//儲存 forKey：唯一標識
[defaults setObject:config forKey:Key];

//同步
[defaults synchronize];

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSMutableDictionary *config = [NSMutableDictionary dictionaryWithDictionary:[defaults objectForKey:Key]];
//config = [[NSUserDefaults standardUserDefaults] objectForKey:Key];