Swift 学习之集合的基本用法

集合的基本用法

数组:有序的数据

1.定义一个数组,并初始化的不同方式

var array1 = []var array2 :[String] = ["hello"]var array3 = [String](count: 1, repeatedValue: "world")var array4 = array2 + array3 // "hello world"if !array4.isEmpty{    print(array4) //hello world}

2.向数组中添加元素或者是修改某个元素的值

array4.append("!")array4 += ["..."]array4 += ["...","....."]array4.insert("first code ", atIndex: 0)array4[0] = "first Item"

3.删除元素的时候，一般都回返回删除的元素

array4.removeAtIndex(0) //删除元素并返回该删除的元素array4.removeFirst()  //"hello"array4.removeLast()  "....."//array4.removeAll() //删除所有元素

4.访问数组元素的值

array4[0] for item in array4{    print(item)}for (index,value) in array4.enumerate(){    print("\(index + 1):\(value)")}

Set :无序的数据集合

1.初始化

var letters = Set<String>()print("letters is of type Set<Character> with \(letters.count) items.")var letters1 :Set = ["1","2","3","4","6","7"]var letters2 :Set = ["2","3"]var letters3 :Set = ["3","8","5"]

2.访问还有修改set的元素

letters1.insert("8")letters1.countif !letters1.isEmpty{    print(letters1)}if let tempItem = letters1.remove("3"){    print(tempItem)}if letters1.contains("1"){    print("letters1 contains 1")}for item in letters1{    print(item)}for item in letters1.sort(){    print(item)}//letters1 = []letters1.removeAll()

3.set 之间的基本操作

var data1 :Set = ["1","2","3","4","6","7"]var data2 :Set = ["2","3"]var data3 :Set = ["4","8","5"]// intersect : 返回set之间相同的数据  data1.intersect(data2) //{"2", "3"}// exclusiveOr:返回两者之间不同的部分 data1.exclusiveOr(data3) //{"2", "1", "8", "6", "4", "7", "5"}//union :返回两者之间所有的数据data1.union(data3) //{"2", "1", "8", "6", "4", "3", "7", "5"}//subTractdata1.subtract(data2) //返回data1中data2不含有的元素//比较两个setif data1 != data2{    print("\(data1) != \(data2)")    //"["4", "2", "1", "7", "6", "3"] != ["2", "3"]}// 是否是父set    if data1.isSupersetOf(data2){        print("\(data1) 包含 \(data2)")        // "["4", "2", "1", "7", "6", "3"] 包含 ["2", "3"]\n"    }//是否是子set    if data2.isSubsetOf(data1){        print("\(data2) 是 \(data1) 的子set")        //"["2", "3"] 是 ["4", "2", "1", "7", "6", "3"] 的子set\n"    }// 是否是子set，但是不相同    if data2.isStrictSubsetOf(data1){        print(data2)        //"["2", "3"]\n"    }// 两个set是否含有相同的元素    if data2.isDisjointWith(data3){        print(data2)        //"["2", "3"]\n"    }

dictonry 字典。无序的键值对

1.初始化

var dict1 :Dictionary = [Int : String ]()dict1 = [1:"one",2:"two",3:"three",4:"four"]var dict2:[String:String] = ["1":"one","2":"two","3":"three","4":"four"]

2.访问或者修改字典的元素

dict2.count //4if !dict2.isEmpty{    print(dict2)    // "["4": "four", "2": "two", "1": "one", "3": "three"]\n"}dict2["3"] = "三"print(dict2) //"["4": "four", "2": "two", "1": "one", "3": "三"]\n"//更改元素并返回if let item = dict2.updateValue("three", forKey: "3"){    print(item)  //"三\n"}if let item = dict2["1"]{    print(item) //one}dict2.removeValueForKey("4") //four,删除指定key的元素，并返回//遍历for (key ,value) in dict2 {    print("\(key) :  \(value)")}for key in dict2.values{    print(key)}for  value in dict2.values{    print(value)}//转换为数组let demos =  [String](dict2.values)print(demos)