用Swift创建一个文件夹

问题描述

我正在使用 NSFileManager 的方法 createDirectoryAtPath：withIntermediateDirectories：attributes：error： in Swift。

I'm trying to use NSFileManager's method createDirectoryAtPath:withIntermediateDirectories:attributes:error: in Swift.

问题是我不知道这个功能是否会在错误的情况下抛出。这是否记录在任何地方？如果是，在哪里？

The problem is that I have no idea what this function throws in case of error. Is this documented anywhere? If yes, where?

推荐答案

当Swift文档说一个函数 throws ，这意味着它会抛出一个 NSError 。

When the Swift docs says a function throws, they mean that it throws an NSError.

考虑以下 do-try -catch flow：

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

do {
    try NSFileManager.defaultManager().createDirectoryAtPath(documentsPath, withIntermediateDirectories: false, attributes: nil)
} catch {
    print(error)
    print(error.dynamicType)
}

createDirectoryAtPath 将失败，因为文档目录已经存在。记录错误中的 dynamicType 表明它实际上是一个 NSError object：

createDirectoryAtPath will fail because the documents directory already exists. Logging the dynamicType of the error shows that it is in fact an NSError object:

Error Domain=NSCocoaErrorDomain Code=516 "The file "Documents" couldn’t be saved in the folder "35B0B3BF-D502-4BA0-A991-D07568AB87C6" because a file with the same name already exists." UserInfo={NSFilePath=/Users/jal/Library/Developer/CoreSimulator/Devices/E8A35774-C9B7-42F0-93F1-8103FBBC7118/data/Containers/Data/Application/35B0B3BF-D502-4BA0-A991-D07568AB87C6/Documents, NSUnderlyingError=0x7fa88bd14410 {Error Domain=NSPOSIXErrorDomain Code=17 "File exists"}}

NSError

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