Swift 数组

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定义数组
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func definitionArr()->(){
   
    var arr:[Any] = []//空 任意类型
    var arr1:[String] = []//空 只能存字符串
    var arr2:[Any] = ["1",1]
    var arr4:[Dictionary] = []
    
    //自动推导的结果[String] ->表示数组中存储的是string
        let array = ["张三","李四","王五"]
        print(array)
        //[Int]->表示数组中存储的是int
        let array2 = [1,2,3,4,5]
        print(array2)
        
        let p = CGPoint(x: 10, y: 300)
        let array3 = [p]
        print(array3)
        
        //混合数组:几乎不用
        //如果类型不一致，自动推导结果为NSObject
        let array4 = ["张三",1,p] as [Any]
        print(array4)
        //定义一个数组，指定类型是int
        var array5 = [Int]()
        for i in 0...8 {
            array5.append(i)
            print("\(array5) \(array5.capacity)")
        }
        
  
}
数组遍历
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// MARK:数组的遍历
    func demo1() {
        let array = ["张三","李四","王五"]
        //1.按照下标遍历
        print("按照下标遍历")
        for i in 0..
            print(array[i])
        }
        //2.for in遍历元素
        print("按照for in遍历元素")
        for s in array {
            print(s)
        }
        //3.同时遍历下标和内容
        print("同时遍历下标和内容")
        //元组
        for e in array.enumerated() {
            print("\(e.offset) \(e.element)")
        }
        //4.遍历下标和内容2
        print("同时遍历下标和内容2")
        for (n,s) in array.enumerated() {
            print("\(n) \(s)")
        }
        //5.反序遍历
        print("反序遍历")
        for s in array.reversed() {
            print(s)
        }
        //6.反序遍历索引和内容
        print("反序遍历索引和内容")
        for (n,s) in array.enumerated().reversed() {
            print("\(n) \(s)")
        }
    }
数组的增删改
增
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func addElement() -> () {
    let arr1 = ["今","天","是","个","好","日","子"]
    var arr = ["今","天","是","个","好","日","子","A","b"]
    //添加数组
    arr.append(contentsOf: arr1)
    //print(arr)
}
删除
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func remove() -> () {
    var arr = ["今","天","是","个","好","日","子","A","b"]
    //删除指定index的元素
    //arr.remove(at: 2)
    //删除最后的一个元素
    //arr.removeLast()
    //删除最前的一个元素
    //arr.removeFirst()
    //单侧删除
    //arr.removeFirst(3)
    //单侧删除
    //arr.removeLast(3)
    //删除所有的元素
    //arr.removeAll()
    //是否保留arr的空间
    arr.removeAll(keepingCapacity: true)
    print(arr)
}
插入
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func insertElement() -> () {
    var arr = ["今","天","是","个","好","日","子","A","b"]
    //插入数据
    arr.insert("1", at: 0)
    //print(arr)
}
修改
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// 这里是var变量， 不能是常量
var array1 = [1, 2, 3, 4, 5]
// 这样子就修改了第一个元素
array1[0] = 9
数组合并
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// MARK:数组合并
   func demo3()  {
       //[String] var array = ["张三","李四","王五"]
       var array = ["张三","李四","王五"] as [Any]
       //[Any]
       let array2 = ["老刀","1","2",180] as [Any]
       //合并
       //注意：合并的两个类型必须一致
       array += array2
       print(array)
   }
数组去重
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func arrRemovingWeight() -> () {
    //数组去重
    #if false
        //方法1 原理：字典中key是唯一的
        let array = [111, 222, 111]
        var dictInts = Dictionary()
        
        for number in array {
            dictInts[String(number)] = number
        }
        
        var result = [Int]()
        for value in dictInts.values {
            result.append(value)
        }
        print(result)
    #endif
    #if false
    //方法2
    let arr = ["1","2","3","4","3"]
    var arr1:[String] = []
    for item in arr {
        
        if !arr1.contains(item){
            arr1.append(item)
        }
    }
    print(arr1)
    #endif
    //数组合并 只要不同的和只要相同的只需要在if的位置加判断即可
    let arr = ["1","2","3","4"]
    var arr1 = ["1","2","4","8"]
    
    for item in arr {
        if !arr1.contains(item){
            arr1.append(item)
        }
    }
    print(arr1)

    //判断数组是否为空
    if arr1.isEmpty {
        
    }
    
}
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