swift如何确定变量是否为可选

本文介绍了swift如何确定变量是否为可选的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想知道变量是否是可选的

I want to know if a variable is an optional

我尝试以下方法，但失败

I try method below, but fail

func isOptional(v: Any) -> Bool { return v is Optional }

推荐答案

作为一项学术练习(可以做还是应该做)，我想出了这一点:

As an academic exercise (can it be done vs. should it be done), I came up with this:

func isOptional(a: Any) -> Bool { return "\(a.dynamicType)".hasPrefix("Swift.Optional") }

示例:

let name = "Fred" let oname: String? = "Jones" let age = 37 let oage: Int? = 38 let arr: [Any] = [name, oname, age, oage] for item in arr { println("\(item) \(isOptional(item))") }

输出:

Fred false Optional("Jones") true 37 false Optional(38) true

我建议在生产代码中使用它吗?否.我建议尽可能远离Any，我不敢打赌dynamicType的输出保持不变.

Would I recommend using this in production code? No. I recommend staying away from Any if at all possible, and I wouldn't bet on the output of dynamicType remaining the same.