黑马程序员---Objective-C NSDictionary

key(（键） ----> value（值）

普通创建

    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"jack" forKey:@"name"];

利用数组创建

    NSArray *keys = @[@"name", @"address"];

    NSArray *objects = @[@"jack", @"北京"];

    NSDictionary *dict = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

快速创建

    NSDictionary *dict = @{@"name" : @"jack", @"address" : @"北京"};

通过key读取字符串

    id obj = dict[@"name"];

返回的是键值对的个数

NSLog(@"%ld", dict.count);

NSMutableDictionary的增添

    NSMutableDictionary *dict = [NSMutableDictionary dictionary];

添加键值对

    [dict setObject:@"jack" forKey:@"name"];

    [dict setObject:@"北京" forKey:@"address"];

    [dict setObject:@"rose" forKey:@"name"];

移除键值对

    [dict removeObjectForKey:  ]