Objective－C（ Foundation框架 一 NSDictionary (NSMutaleDictionary)）

NSDictionary

不可变的字典

创建字典的方法

        // 创建字典的方式
        NSDictionary *dy = [NSDictionary dictionaryWithObject:@"a"forKey:@"b"];
        NSDictionary *dy1 = [NSDictionary dictionaryWithObjectsAndKeys:@"a",@"b",@"c",@"d" ,nil];

        // 快速创建字典
        // 重复key值，重复的不能保存到字典中
        NSDictionary *dy2 = @{@"we":@"haha", @"we":@"ha"};

        NSLog(@"%@",dy);
        NSLog(@"%@",dy1);
        NSLog(@"%@",dy2);

获取字典的长度

        // 获取字典长度
        NSDictionary *dy2 = @{@"we":@"haha", @"w":@"ha"};
        NSLog(@"%lu",dy2.count); // 输出2
        // 如果key值重复，长度不计算在内
        NSDictionary *dy2 = @{@"we":@"haha", @"we":@"ha"};
        NSLog(@"%lu",dy2.count); //输出1 

字典的遍历

        NSDictionary *dy1 = [NSDictionary dictionaryWithObjectsAndKeys:@"a",@"b",@"c",@"d" ,nil];

        // 快速创建字典
        // 重复key值，重复的不能保存到字典中
        NSDictionary *dy2 = @{@"we":@"haha", @"w":@"ha"};
        NSLog(@"%lu",dy2.count);

        // 字典的遍历
        for (NSString *key in dy2) {
            NSLog(@"key = %@, value = %@", key, [dy2 objectForKey:key]);
        }
        // 枚举类型遍历
        [dy1 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
            NSLog(@"key = %@, value = %@", key, obj);
        }];

把字典存到文件中

        // 把字典保存到文件中
        NSDictionary *dy2 = @{@"we":@"haha", @"w":@"ha"};
        BOOL isWrite = [dy2 writeToFile:@"/Users/cloudwalk/Desktop/test.plist" atomically:YES];
        if (isWrite) {
            NSLog(@"写入成功");
        }

从文件中读取字典

        NSDictionary *readDy2 = [NSDictionary dictionaryWithContentsOfFile:@"/Users/cloudwalk/Desktop/test.plist"];
        NSLog(@"%@",readDy2);
        

通过把数组添加到字典中，构建成数组字典

        NSArray *sdArr = [NSArray arrayWithObjects:@"zaozhuang",@"jinan",nil];
        NSArray *jxArr = [NSArray arrayWithObjects:@"jiujiang",@"nanchang",nil];
        NSDictionary *citys = [NSDictionary dictionaryWithObjectsAndKeys:sdArr,@"sd",jxArr,@"jx", nil];
        NSLog(@"citys = %@",citys);

        NSDictionary *citys = [NSDictionary dictionaryWithObjectsAndKeys:sdArr,@"sd",jxArr,@"jx", nil];
        NSLog(@"citys = %@",citys);
        // 把citys存到文件中
        [citys writeToFile:@"/Users/cloudwalk/Desktop/test1.plist" atomically:YES];

NSMutableDictionay

    // 创建可变字典
    NSMutableDictionary *dy1 = [NSMutableDictionary dictionary];

    //  添加键值对
    [dy1 setValue:@"lili" forKey:@"is"];
    [dy1 setValue:@"heihei" forKey:@"hah"];
    NSLog(@"%@",dy1);

    // 删除某个键值对
    //[dy1 removeObjectForKey:@"is"];
    NSLog(@"%@",dy1);

    // 快速修改键值对
    dy1[@"is"] =@"xossk";
    NSLog(@"%@",dy1);

    // 修改键值对
    [dy1 setObject:@"xixi" forKey:@"is"];
    NSLog(@"%@",dy1);