swift 5.0 数组相关函数

1、数组添加某一个值

        var arradd = ["11","22","33","44","55"]
        print("arradd返回的类型是:--->\(type(of: arradd))");
        print("arradd=\(arradd)");

        //数组添加某一个值
        arradd.append("66")//向数组最后添加一个元素
        print("arradd=\(arradd)");
        
        arradd.insert("77", at: 2)//向数组下标为2的地方插入一个元素
        print("arradd=\(arradd)");
        
        
        let arradd1 = ["0011","0022","0033","0044","0055"]
        arradd.append(contentsOf: arradd1)//向数组末尾插入数组
        print("arradd=\(arradd)");

        let arradd2 = ["啦啦","哈哈","嗷嗷","啊啊","永远"]
        arradd.insert(contentsOf: arradd2, at: 4)//向数组下标为4的地方插入一个数组
        print("arradd=\(arradd)");

2、数组删除某一个值

       var arrdelete = ["11","22","33","44","55","66","77","88","99"]
        print("arrdelete返回的类型是:--->\(type(of: arrdelete))");
        print("arrdelete=\(arrdelete)");
        
        arrdelete.remove(at: 2)//根据下标移除元素
        print("arrdelete=\(arrdelete)");
        
        arrdelete.removeFirst()//移除数组中第一个元素
        print("arrdelete=\(arrdelete)");
        
        
        arrdelete.removeLast()//移除数组中最后一个元素
        print("arrdelete=\(arrdelete)");
        print("------------------  这个是一个分割线  ---------------")
        
        var arrdelete1 = ["11","22","33","44","55","66","77","88","99"]
        print("arrdelete1=\(arrdelete1)");

        arrdelete1.removeFirst(3)//移除数组中前3个元素
        print("arrdelete1=\(arrdelete1)");
        
        arrdelete1.removeLast(2)//移除数组中后2个元素
        print("arrdelete1=\(arrdelete1)");
        
        arrdelete1.removeAll()//移除数组中所有元素
        print("arrdelete1=\(arrdelete1)");

3、获取指定位置数据

        let arrget =  ["11","22","33","44","55","66","77","88","99"]
        print("arrget=\(arrget)");
        
        print("arrget第一个元素=\(arrget.first!)")//获取素组中第一个元素
        
        print("arrget最后一个元素=\(arrget.last!)")//获取数组中最后一个元素
        
        print("arrget下标为5的元素=\(arrget[5])")//获取数组中下标为5的元素

4、数组遍历

        let arrtraverse =  ["11","22","33","44","55","66","77","88","99"]
        print("arrtraverse=\(arrtraverse)");

第一种： for - in

        for model in arrtraverse{
            print("值为:\(model)");
        }

第二种：区间遍历

        for idx in 0...arrtraverse.count-1 {
            print("下标为:\(idx)  值为:\(arrtraverse[idx])");
            }

第三种：反向遍历

           for idx in arrtraverse.reversed() {
               print("反向：idx =\(idx)");
           }

第四种：有时候我们需要知道当前遍历数组的下标

        for model in arrtraverse.enumerated(){
            print("下标为:\(model.offset)  值为:\(model.element)");
        }

第五种：map

        arrtraverse.map { (element) in
            print("值为:\(element)");
        }

第六种：forEach

        arrtraverse.forEach { (element) in
            print("值为:\(element)");
        }

第七种：跨步遍历（如：从0开始每隔2个打印一次）

        for idx in stride(from: arrtraverse.startIndex, to: arrtraverse.endIndex, by: 2) {
               print("跨步idx = \(arrtraverse[idx])");
           }

根据某一条件获取符合条件的元素（如：找出数组中大于3的元素）

        let arrInt:[Int] = [1,2,3,4,5]
        let result = arrInt.filter { (element) -> Bool in
            
            return element > 3
        }
        print("值为:\(result)");

5、数组包含

        let arrcontains =  ["11","22","33","44","55","66","77","88","99"]
        print(arrcontains.contains("55"))

6、数组最值

        let arrInt1:[Int] = [1,2,3,4,5]
        print((arrInt1.max()!))
        print((arrInt1.min()!))

7、数组排序
升序

        let arrInt2 = [1,2,9,3,6,4,10,5]
        let result1 = arrInt2.sorted()//数组升序
        print(result1)

        //也可以这样写
//        let result1 =  arrInt2.sorted { (x, y) -> Bool in
//             return x < y
//         }

降序

       let result2 =  arrInt2.sorted { (x, y) -> Bool in
            return x > y
        }
        print(result2)

常用例子

        var userList = [UserInfo]()
        let userinfo1 = UserInfo()
        userinfo1.name = "张三"
        userinfo1.phone = "4234"
        userinfo1.age = 29

        userList.append(userinfo1)
        
        let userinfo2 = UserInfo()
        userinfo2.name = "李四"
        userinfo2.phone = "1212"
        userinfo2.age = 40
        userList.append(userinfo2)
        
        let userinfo4 = UserInfo()
        userinfo4.name = "赵六"
        userinfo4.phone = "1232"
        userinfo4.age = 30
        userList.append(userinfo4)
        
        
        let userinfo3 = UserInfo()
        userinfo3.name = "王五"
        userinfo3.phone = "3525"
        userinfo3.age = 25
        userList.append(userinfo3)
        
        userList.forEach { (model) in
            print(model.name!)
        }

        
        print("------------------  这个是一个分割线  ---------------")
        let aa =  userList.sorted { (model1:UserInfo, model2:UserInfo) -> Bool in
            return model1.age! <  model2.age!
        }
        
        aa.forEach { (model) in
            print(model.name!)
        }


class UserInfo {
    var name:String?
    var phone:String?
    var age:Int?
}