如果设置了功能，为什么仍存在未解决的标识符？

Question

我已经设置了以下两个功能：getDirectory和displayAlert。我确定我没有把它们拼错。但是，为什么仍然存在未解决的标识符？谢谢！

        let filename = getDirectory().appendingPathComponent("\(numberOfRecords).m4a") 

        catch
        {
            displayAlert(title:"Oops!", message: "Recording failed")
        }





   func getDirectory() -> URL
   {
    let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
    let documentDirectory = paths[0]
    return documentDirectory
    }

    func displayAlert(title:String, message:String){
        let alert = UIAlertController(title:title, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title:"dismiss", style: .default, handler: nil))
        present(alert, animated: true, completion: nil)
    }[enter image description here][1]