一、NSDictionary的创建

//字典的创建
    NSDictionary *dic1 = @{@"name":@"李四", @"age":@(24)};
    //这种创建字典的方式   前面的为value后面跟的是key
    NSDictionary *dic2 = [NSDictionary dictionaryWithObjectsAndKeys:@"李四", @"name", @(24), @"age", nil];
    NSDictionary *dic3 = [NSDictionary dictionaryWithDictionary:dic1];
    NSDictionary *dic4 = [[NSDictionary alloc] init];
    NSDictionary *dic5 = [[NSDictionary alloc] initWithObjectsAndKeys:@"李四", @"name", @(24), @"age", nil];
    NSDictionary *dic6 = [[NSDictionary alloc] initWithDictionary:dic1];
    NSLog(@"%@, %p", dic1, dic1);
    NSLog(@"%@, %p", dic2, dic2);
    NSLog(@"%@, %p", dic3, dic3);
    NSLog(@"%@, %p", dic4, dic4);
    NSLog(@"%@, %p", dic5, dic5);
    NSLog(@"%@, %p", dic6, dic6);
2018-06-28 14:03:47.056395+0800 NSDictionaryDemo[8144:477685] {
    age = 24;
    name = "\U674e\U56db";
}, 0x600000470640
2018-06-28 14:03:47.056587+0800 NSDictionaryDemo[8144:477685] {
    age = 24;
    name = "\U674e\U56db";
}, 0x600000470f40
2018-06-28 14:03:47.056775+0800 NSDictionaryDemo[8144:477685] {
    age = 24;
    name = "\U674e\U56db";
}, 0x600000470640
2018-06-28 14:03:47.057237+0800 NSDictionaryDemo[8144:477685] {
}, 0x60000000dd30
2018-06-28 14:03:47.057511+0800 NSDictionaryDemo[8144:477685] {
    age = 24;
    name = "\U674e\U56db";
}, 0x600000471200
2018-06-28 14:03:47.057997+0800 NSDictionaryDemo[8144:477685] {
    age = 24;
    name = "\U674e\U56db";
}, 0x600000470640

二、NSDictionary常用属性

    NSDictionary *dic = @{@"name":@"李四", @"age":@(24)};
    //获取字典中键值对个数
    NSLog(@"%ld", dic.count);
    //获取字典中的所有key
    NSLog(@"%@", dic.allKeys);
    //获取字典中的多有value
    NSLog(@"%@", dic.allValues);
2018-07-02 14:55:28.644107+0800 NSDictionaryDemo[4830:308743] 2
2018-07-02 14:55:28.644297+0800 NSDictionaryDemo[4830:308743] (
    name,
    age
)
2018-07-02 14:55:28.644470+0800 NSDictionaryDemo[4830:308743] (
    "\U674e\U56db",
    24
)

三、NSDictionary常用方法

    NSDictionary *dic = @{@"name":@"李四", @"age":@(24)};
    //通过key值来获取它多对应的value
    NSLog(@"%@", [dic objectForKey:@"name"]);
    //遍历字典中的数据
    [dic enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        NSLog(@"key:%@ value:%@", key, obj);
    }];
    //根据value值排序，得到key数组
    NSArray *keyArr = [dic keysSortedByValueUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        NSString *str1 = [NSString stringWithFormat:@"%@", obj1];
        NSString *str2 = [NSString stringWithFormat:@"%@", obj2];
        return [str1 compare:str2];
    }];
    NSLog(@"%@", keyArr);
2018-07-02 15:06:13.766435+0800 NSDictionaryDemo[5039:322548] 李四
2018-07-02 15:06:13.766611+0800 NSDictionaryDemo[5039:322548] key:name value:李四
2018-07-02 15:06:13.766743+0800 NSDictionaryDemo[5039:322548] key:age value:24
2018-07-02 15:06:13.767102+0800 NSDictionaryDemo[5039:322548] (
    age,
    name
)

四、NSMutableDictionary的使用

    //NSMutableDictionary继承于NSDictionary，所以上面说到的方法和属性，NSMutableDictionary依然适用
    NSMutableDictionary *muDic1 = [NSMutableDictionary dictionary];
    //创建一个开辟空间大小为1的字典，如果超过他会自动扩大
    NSMutableDictionary *muDic2 = [NSMutableDictionary dictionaryWithCapacity:1];
    
    //向字典中添加数据
    [muDic1 setObject:@"李四" forKey:@"name"];
    NSLog(@"%@", muDic1);
    [muDic1 setValue:@(24) forKey:@"age"];
    NSLog(@"%@", muDic1);
    
    //根据key值删除字典中的数据
    [muDic1 removeObjectForKey:@"age"];
    NSLog(@"%@", muDic1);
    //删除字典中的所有数据
    [muDic1 removeAllObjects];
    NSLog(@"%@", muDic1);
    
    [muDic1 setObject:@"李四" forKey:@"name"];
    [muDic1 setValue:@(24) forKey:@"age"];
    [muDic1 setValue:@"boy" forKey:@"sex"];
    
    //根据key值数组删除对应的数据
    [muDic1 removeObjectsForKeys:@[@"age", @"name"]];
    NSLog(@"%@", muDic1);
    
    //向字典中添加数据的时候，如果key值已经存在那么后来添加同样key值数据，就会覆盖以前的数据
    [muDic1 setObject:@"girl" forKey:@"sex"];
    NSLog(@"%@", muDic1);
    
    [muDic2 setObject:@"shanghai" forKey:@"address"];
    [muDic2 setObject:@"3000" forKey:@"income"];
    
    //把另一个字典中的所有数据添加到当前字典中。当出现相同key的时候，后面的值也会覆盖原值
    [muDic1 addEntriesFromDictionary:muDic2];
    NSLog(@"%@", muDic1);
2018-07-02 15:28:58.889004+0800 NSDictionaryDemo[5375:350081] {
    name = "\U674e\U56db";
}
2018-07-02 15:28:58.889190+0800 NSDictionaryDemo[5375:350081] {
    age = 24;
    name = "\U674e\U56db";
}
2018-07-02 15:28:58.889317+0800 NSDictionaryDemo[5375:350081] {
    name = "\U674e\U56db";
}
2018-07-02 15:28:58.889429+0800 NSDictionaryDemo[5375:350081] {
}
2018-07-02 15:28:58.889676+0800 NSDictionaryDemo[5375:350081] {
    sex = boy;
}
2018-07-02 15:28:58.889766+0800 NSDictionaryDemo[5375:350081] {
    sex = girl;
}
2018-07-02 15:28:58.889875+0800 NSDictionaryDemo[5375:350081] {
    address = shanghai;
    income = 3000;
    sex = girl;
}