swift 数组

本文为OC开发者转swift时，遇到的各种小白问题，贻笑大方，仅为个人学习历程。

swift数组基本操作:

//数组初始化
var arr = [String]()
//添加
arr.append("111")//["111"]
arr.insert("222", at: 0)//["222","111"]
arr += ["333","555","666","777"]//["222","111","333","555","666","777"]
//修改
arr[2] = "444"//["222","111","444","555","666","777"]
//删除
arr.remove(at: 0)//["111","444","555","666","777"]
arr.removeAll { (object) -> Bool in
    return object == "111"
}//["444","555","666","777"]
arr.removeFirst()//["555","666","777"]
arr.removeLast(2)//["555"]删除最后两个数组元素
arr.removeAll()//[]

swift中的几个好用的方法：

1、filter：返回值是数组

chatList.filter { (model) -> Bool in
    return model.mid == "111"
}//["555","666","777"]

2、first：返回值是数组里的元素

let list = arr.first { (item) -> Bool in
    return item > "444"
}//"444"

3、sort：排序

let list = arr.sorted { (item1, item2) -> Bool in
    return item1 > item2
}//["777","666","555","444","222","111"]

4、map：返回一个新数组，原数组不变

let list = arr.map { (item) -> Int in
    return Int(item) ?? 0
}[222,111,444,555,666,777]