Swift学习笔记-字典Dictionary

//字典
        //声明
        //1.泛型语法声明
        var myDict : Dictionary<String,String>
        //2.使用简化语法声明
        var dictText : [String:Int]
        var dictText1 : [String:String]
        //赋值
        //1.创建一个字典结构体，使用默认的参数
        myDict = Dictionary<String,String>()
        println(myDict)//[:]
        dictText = Dictionary<String,Int>(minimumCapacity: 5)
        println(dictText)
        //2.使用简化语法创建字典
        dictText1 = ["high":"20","fat":"110"]
        println(dictText1)//[fat: 110,high: 20]
        //创建不包含任何key-value对的字典
        var emptyDic : [String:Double] = [:]
        //isEmpty属性可判断数组，字典是否不包含任何元素
        println(emptyDic.isEmpty) //true

        var em : [String:String]
        em = Dictionary()
        println(em.isEmpty)

        //字典的使用
        var high = dictText1["high"]
        println(high)//Optional("20")
        //访问不存在的key返回nil
       var tro = dictText1["tro"]
        println("\(tro)")//nil
        //修改指定的key对应的value
        dictText1["fat"] = "200"
        println(dictText1)//[fat: 200,high: 20]
        //如果key不存在，则添加
        dictText1["pressure"] = "112"
        println(dictText1)//[fat: 200,high: 20,pressure: 112]
        //如果需要返回key对应的value需要加“！”强制解析
        var englis : String? = dictText1["high"]
        if englis != nil
        {
            println(englis!)
        }

var result = dictText1.updateValue("289",forKey: "fat")
        println("result is \(result)")//result is Optional("200")
        println(dictText1)//[fat: 289,pressure: 112]

        /** for in遍历字典 */
        var seasons = ["a":"测试","b":"summer","c":"autumn"]
        /** * b:summer a:测试 c:autumn */
        for (season,desc) in seasons
        {
            println("\(season):\(desc)")
        }

        /** 单独使用字典的keys和values */
        var keys = Array(seasons.keys)
        var valuess  = Array(seasons.values)
        println("\(keys)....\(valuess)")//[b,a,c]....[summer,测试,autumn]

        //删除
        seasons.removeValueForKey("d")
        /** [b: summer,a: 测试,c: autumn] */
        println(seasons)
        seasons.removeValueForKey("c")
        //[b: summer,a: 测试]
        println(seasons)
        //通过将value赋值为nil来删除
        seasons["b"] = nil
        println(seasons)//[a: 测试]

部分内容来自于<疯狂Swift讲义>

原文地址：https://www.jb51.cc/swift/327059.html