Swift编程基础(三):数组与字典
2016-04-07 07:26
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数组
数组的初始化
let arr1 = ["a","b","c"] let arr2:[String] = ["a","b","c"] let arr3 = [String](count:3 repeatedValue:"a") //arr1为:["a", "b", "c"] //arr2为:["a", "b", "c"] //arr3为:["a", "a", "a"]
数组的插入
var arr = ["a","b","c"] arr += ["d"] //arr为:["a", "b", "c", "d"] arr.appendContentsOf(["e"]) //arr为:["a", "b", "c", "d","e"] arr.append("f") //arr为:["a", "b", "c", "d","e","f"] arr.insert("g", atIndex: arr.endIndex.advancedBy(0)) //arr为:["a", "b", "c", "d","e","g"] arr.insertContentsOf(["h","i"],at:arr.endIndex.advancedBy(-1)) //arr为:["a", "b", "c", "d", "e", "f", "h", "i", "g"]
数组的删除
arr.removeFirst() //arr为:["b", "c", "d", "e", "f", "h", "i", "g"] arr.removeLast() //arr为:["b", "c", "d", "e", "f", "h", "i"] arr.removeAtIndex(1) //arr为:["b", "d", "e", "f", "h", "i"] arr.removeFirst(2) //arr为:["e", "f", "h", "i"] arr.removeRange(Range(start:arr.startIndex.advancedBy(0), end: arr.endIndex.advancedBy(-1))) //arr为:["i"]
数组的值修改
var shopList = ["egg","cheese","butter"] shopList[0] = "chocolate" //shopList为:["chocolate", "cheese", "butter"] shopList[1...2] = ["apple","banana"] //shopList为:["chocolate", "apple", "banana"] shopList.replaceRange(Range(start:shopList.startIndex.advancedBy(0),end:shopList.endIndex.advancedBy(-1)), with: ["egg","cheese"]) //shopList为:["egg","cheese","banana"]
字典
字典的初始化
let dic1:Dictionary<String,[String]> = ["1":["a","b"],"2":["b","c"]] //真是一个value为数组的字典,dic1为:["2": ["b", "c"], "1": ["a", "b"]] let dic2:Dictionary<Int,String> = [1:"ni",2:"hao"] //真是一个key为Int类型的字典,dic2为:[2: "hao", 1: "ni"] var dic = [1:"first","2":["q","e"]] //dic为[1: first, 2: (q,e)]。这样的初始化,dic打印出来的结果跟上面两种初始化方式有所不同,key关键字为 字符串时并没有双引号;value为数组时也不是用中括号表达,而是用的小括号,说明此时的数组是Optional可选类型。
字典值修改
dic[1] = "second" //dic为:[1: second, 2: (q,e)] dic.updateValue("third", forKey: 1) //dic为:[1: third, 2: (q,e)]
字典值移除
dic.removeValueForKey("2") //dic为:[1: third] dic[1] = nil //dic为:[:]字典添加元素var dic:Dictionary<String,String> =["a":"banana","b":"apple"] dic["c"] = "pear" print(dic) //输出:["b": "apple", "a": "banana", "c": "april"]
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