Swift 共享文件操作小结（iOS 8 +）

 private let VIDEO_EXTENSIONS = [
    ".MOV", ".MP4"
  ]

  private var fileManager = NSFileManager.defaultManager()
  
  func loadVideos() {
    var paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    if paths.count > 0 {
      let documentsDirectory = paths[0] as String
      let documentUrl = NSURL(fileURLWithPath: documentsDirectory, isDirectory: true)
      do {
        documentUrl.path
        let files = try fileManager.contentsOfDirectoryAtPath(documentsDirectory)
        for file in files {
          fetchVideos(documentUrl.URLByAppendingPathComponent(file).path ?? "")
        }
      }  catch {
        
      }
      
      self.tableView.reloadData()
    }
  }
  
  func fetchVideos(path: String) {
    var isDir: ObjCBool = false
    if !path.isEmpty && fileManager.fileExistsAtPath(path, isDirectory: &isDir) {
      if isDir {
        do {
          let files = try fileManager.contentsOfDirectoryAtPath(path)
          for file in files {
            fetchVideos(file)
          }
        } catch {
        }
      } else {
        var file = File(path: path)
        if file.isValid() && isVideoFileExtension(file.fileExtension.uppercaseString) {
          do {
            if let attr: NSDictionary = try fileManager.attributesOfItemAtPath(path) {
              file.fileSize = attr.fileSize()
            }
          } catch {
          }
          videos.append(file)
        }
      }
    }
  }
  
  func isVideoFileExtension(ext: String) -> Bool {
    for videoExtension in VIDEO_EXTENSIONS {
      if ext == videoExtension {
        return true
      }
    }
    return false
  }
  
  struct File {
    var fileExtension = ""
    var fileName = ""
    var path = ""
    var assert: AVURLAsset?
    var url: NSURL!
    var fileSize: UInt64 = 0
    
    init(path: String) {
      self.path = path
      self.url = NSURL(fileURLWithPath: path)
      self.fileName = url.lastPathComponent ?? ""
      self.fileExtension = "." + (url.pathExtension ?? "")
    }
    
    func isValid() -> Bool {
      return !(fileName.isEmpty || fileExtension.isEmpty)
    }
  }

 func play(file: File) {
    let player = AVPlayer(URL: file.url)
    let playerViewController = AVPlayerViewController()
    playerViewController.player = player
    self.presentViewController(playerViewController, animated: true) {
      playerViewController.player?.play()
    }
  }

 func openIn(file: File, indexPath: NSIndexPath) {
    let document = UIDocumentInteractionController(URL: file.url)
    let rect = self.tableView.rectForRowAtIndexPath(indexPath)
    document.presentOpenInMenuFromRect(rect, inView: self.tableView, animated: true)
  }

 func delete(file: File, indexPath: NSIndexPath) {
    do {
      try fileManager.removeItemAtPath(file.path)
      videos.removeAtIndex(indexPath.row)
      tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
    } catch {
      
    }
  }

 func saveToCameraRoll(file: File, indexPath: NSIndexPath) {
    if UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(file.path) {
      UISaveVideoAtPathToSavedPhotosAlbum(file.path, self, "image:didFinishSavingWithError:contextInfo:", nil)
    } else {
      // save faild
    }
  }
  
  func image(image: UIImage, didFinishSavingWithError error: NSErrorPointer, contextInfo:UnsafePointer<Void>) {
    if error == nil {
      // save success
    } else {
      // save faild
    }
  }