iOS NSUserDefaults轻量级本地存储

NSUserDefaults *ud=[NSUserDefaults standardUserDefaults];
NSDictionary * dict1=@{
@"name":@"Josone",
@"age":@"18",
@"sex":@"M"
};
NSDictionary * dict2=@{
@"name":@"LiHua",
@"age":@"48",
@"sex":@"M"
};
NSDictionary * dict3=@{
@"name":@"Peter",
@"age":@"28",
@"sex":@"M"
};
NSArray *arr=@[dict1,dict2,dict3];
//如果储存内容重名了，会进行替换
[ud setObject:arr forKey:@"班级"];

//马上执行将内容存到硬盘，不写的话，会先缓存，然后在系统不忙的时候储存到硬盘
[ud synchronize];