Swift 3.0 FileManager.fileExists(atPath :)始终返回false [英] Swift 3.0 FileManager.fileExists(atPath:) always return false

问题描述

当我使用方法.fileExists(atPath:)来判断文件在文件系统中是否存在时，该方法总是向我返回false.我检查了文件系统，发现文件确实存在.这是我的代码:

When I use method .fileExists(atPath:)to judge whether the file is exist in file system, the method always return false to me. I checked the file system and the file do exist. Here is my code:

let filePath = url?.path
var isDir : ObjCBool = false
if(self.fileManager.fileExists(atPath: filePath!, isDirectory: &isDir)){
     let result = NSData(contentsOfFile: filePath!)
}

或

let filePath = url?.path
if(self.fileManager.fileExists(atPath: filePath!)){
     let result = NSData(contentsOfFile: filePath!)
}

if子句将始终被跳过.

the if clause will always be skipped.

推荐答案

我假设您的url是URL类型.如果是这样，请尝试以下方法:

I assume your url is an URL type. If so try this out:

let filePath = url?.path  // always try to work with URL when accessing Files
if(FileManager.default.fileExists(atPath: filePath!)){  // just use String when you have to check for existence of your file
    let result = NSData(contentsOf: url!)  // use URL instead of String
}

说够了，您应该像这样更改实现:

Saying enough, you should change your implementation like this:

if(FileManager.default.fileExists(atPath: (url?.path)!)){  // just use String when you have to check for existence of your file
    let result = NSData(contentsOf: url!)  // use URL instead of String
}

1

还有更好的方法，您可以将其称为快速方法(:D).您无需明确检查文件是否存在.

There is even more better way, you can call it swift-way (:D). You don't have to explicitly check for file existence.

guard let result = NSData(contentsOf: fileURL) else {
    // No data in your fileURL. So no data is received. Do your task if you got no data
    // Keep in mind that you don't have access to your result here.
    // You can return from here. 
    return
}
// You got your data successfully that was in your fileURL location. Do your task with your result.
// You can have access to your result variable here. You can do further with result constant.
print(result)

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