ios常见类

NSUserDefaults:

// 存取一些短小的信息
NSString *str = [NSString stringWithString @"hahaha"];
NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];
[ud setObject:str forKey:@"myKey"];  // 设置
NSString *value;
value = [ud objectForKey:"myKey"];   // 读取