如何在 Swift 中找到 NSDocumentDirectory? [英] How to find NSDocumentDirectory in Swift?

问题描述

我正在尝试使用代码获取 Documents 文件夹的路径:

I'm trying to get path to Documents folder with code:

var documentsPath = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory:0,NSSearchPathDomainMask:0,true)

但 Xcode 给出错误:Cannot convert expression's type 'AnyObject[]!'输入'NSSearchPathDirectory'

but Xcode gives error: Cannot convert expression's type 'AnyObject[]!' to type 'NSSearchPathDirectory'

我正在尝试了解代码中的问题.

I'm trying to understand what is wrong in the code.

推荐答案

显然，编译器认为 NSSearchPathDirectory:0 是一个数组，当然它期望的类型是 NSSearchPathDirectory 代替.当然不是有用的错误消息.

Apparently, the compiler thinks NSSearchPathDirectory:0 is an array, and of course it expects the type NSSearchPathDirectory instead. Certainly not a helpful error message.

但至于原因:

首先，您混淆了参数名称和类型.看一下函数定义:

First, you are confusing the argument names and types. Take a look at the function definition:

func NSSearchPathForDirectoriesInDomains(
    directory: NSSearchPathDirectory,
    domainMask: NSSearchPathDomainMask,
    expandTilde: Bool) -> AnyObject[]!

• directory 和 domainMask 是名称，您使用的是类型，但无论如何您应该将它们保留在函数之外.它们主要用于方法.
• 另外，Swift 是强类型的，所以你不应该只使用 0.而是使用枚举的值.
• 最后，它返回一个数组，而不仅仅是一个路径.
• directory and domainMask are the names, you are using the types, but you should leave them out for functions anyway. They are used primarily in methods.
• Also, Swift is strongly typed, so you shouldn't just use 0. Use the enum's value instead.
• And finally, it returns an array, not just a single path.

这样我们就可以了(针对 Swift 2.0 进行了更新):

So that leaves us with (updated for Swift 2.0):

let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0]

对于 Swift 3:

and for Swift 3:

let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]

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