Swift 字典

定义字典

常量

//Swift中用[]
        //[String : Any]
        let dic = ["name":"zhang","age":18] as [String : Any]
        print(dic)
        //定义字典的数组
        let array:[[String:Any]] =[["name":"zhang","age":18],["name":"li","age":180]]
        print(array)

变量

var dictionary: [String:Int] = [:]
var dictionary1 = ["key1": 55, "key2": 555]
var dictionary2 = Dictionary()

字典增删改

//可变var 不可变let
      var dic = ["name":"zhang","age":18] as [String : Any]

增

//增
dic["title"] = "大哥"
print(dic)
// 如果key不存在，则添加新元素
dic.updateValue("XXX", forKey: "number")

改

//修改 通过key修改，key是唯一的
dic["name"] = "大西瓜"
print(dic)
// 如果key存在，则修改value
dic.updateValue("XXX", forKey: "name")

删除

//删除 -直接给定key
//字典通过key来定位置，key必须是可以”hash 哈希“MD5一种
//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
dic.removeAll()     // 删除所有元素
dic.removeValue(forKey: "age")
print(dic)

字典遍历

let dic = ["name":"zhang","age":18,"title":"老板"] as [String : Any]
      for e in dic {
          print("\(e.key) \(e.value)")
      }
   
      for (key,value) in dic {
          print("\(key) \(value)")
      }

字典合并

var dic = ["name":"zhang","age":18,"title":"老板"] as [String : Any]
let dic1 = ["name":"大瓜","height":1.9] as [String : Any]
      //字典不能直接相加
      //思路，遍历dic1依次设置
      //如果key存在,会修改
      //如果key不存在，会新增!
      for e in dic1 {
          dic[e.key] = dic1[e.key]
      }
      print(dic)