OC字典

创建初始化

//参数格式: value1,key1, value2,key2, …..
NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:
@”zhangsan,B,13611112222”, @”zhangsan”,
@”lisi,G,1101101101110”, @”lisi”,
nil];

使用其中对象

NSString *str = [dict objectForKey:@”lisi”];

快速遍历

//细节1: 使用forin获取到的都是key,不是值
//细节2: 使用字典, 存进去是某个顺序, 取出来不一定是这个顺序
for (NSString *key in dict) {
NSString *value = [dict objectForKey:key];
NSLog(@”key = %@, value = %@”,key,value);
}

==NSMutableDictionary==

NSMutableDictionary类继承与NSDictionary

创建对象

NSMutableDictionary *mdict = [[NSMutableDictionary alloc] init];

添加或替换

//细节: 如果这个key不存在, 相当于字典中添加一个对象
//如果key存在, 则会覆盖这个key对应的值
[mdict setValue:@”zhangsan,27” forKey:@”zs”];
[mdict setValue:@”lisi,30” forKey:@”ls”];

移除对象

[mdict removeObjectForKey:@”ww”];
[mdict removeAllObjects];