009-字典

1、定义字典

func demo() {
        //1、定义一个字典
        //[KEY: VALUE] = ["name" : "张", "age" : 18]
        let dict: [String : Any] = ["name" : "Raven", "age" : 25]
        print(dict)
        //输出结果：["name": "Raven", "age": 25]
        
        //2、定义一个数组，元素为字典
        let array = [
            ["name" : "z", "age" : 12],
            ["name" : "w", "age" : 13]
        ]
        print(array)
        //输出结果：[["name": "z", "age": 12], ["name": "w", "age": 13]]
    }

2、增、删、改

func demo1() {
        var dict:[String:Any] = ["name" : "zhang", "age" : 19]
       
        //1、增
        dict["title"] = "大哥"
        print(dict)
        //输出结果：["name": "zhang", "age": 19, "title": "大哥"]
        
        //2、修改
        dict["name"] = "wang"
        print(dict)
        //输出结果：["name": "wang", "age": 19, "title": "大哥"]

        
        //3、删除
        //字典是通过 KEY 来定位值的， KEY 必须是可以 ‘hash哈希’MD5就是一种
        //hash 就是将字符串变成唯一的 ‘整数’， 便于查找，提高字典遍历的速度
        dict.removeValue(forKey: "age")
        print(dict)
        //输出结果：["name": "wang", "title": "大哥"]
    }

3、遍历

func demo2() {
        let dict:[String:Any] = ["name" : "zhang", "age" : 19]
        
        for e in dict {
            print("\(e.key)-\(e.value)")
//            输出结果：
//            name-zhang
//            age-19

        }
    }

4、合并

    func demo3() {
        var dict:[String:Any] = ["name" : "Raven", "age" : 20, "title" : "老板"]
        let dict1:[String:Any] = ["name" : "小明", "height" : 190]
        
        for e in dict1 {
            dict[e.key] = dict1[e.key]
        }
        
        print(dict)
        //输出结果：["name": "小明", "age": 20, "title": "老板", "height": 190]
    }