ios - pathExtension 不可用 : Use pathExtension on NSURL instead. Swift 2.0

Question

我从文档目录中获取 mp3 文件，我写了 pathExtension 等于“mp3”，在 Swift 1.2 中它正在工作，但在 Swift 2.0 中我收到错误“‘pathExtension’不可用:改为在 NSURL 上使用 pathExtension。 “

 func fetchFilesFromFolder() {
        let fileManager = NSFileManager.defaultManager()
        let folderPathURL = fileManager.URLsForDirectory(NSSearchPathDirectory.DocumentDirectory, inDomains: NSSearchPathDomainMask.UserDomainMask)[0]
        if let directoryURLs = try? fileManager.contentsOfDirectoryAtURL(folderPathURL, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions.SkipsHiddenFiles) {
            listOfMP3Files = directoryURLs.map(){ $0.lastPathComponent! }.filter(){ $0.pathExtension == "mp3" } // error is here
        }
    }

Answer 1

或者你可以使用这个扩展:

extension String {
    var ns: NSString {
        return self as NSString
    }
    var pathExtension: String {
        return ns.pathExtension
    }
    var lastPathComponent: String {
        return ns.lastPathComponent
    }
}