NSTemporaryDirectory or documentDirectory : Which one is safest to store data?

I am using Alamofire for download data from the server. I wanted to save in directory whichever is the safest place(DocumentDirectory, NSTemporaryDirectory). Could anyone help me in this?

DocumentDirectory:

   let destination: DownloadRequest.DownloadFileDestination = { _, _ in
        let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let fileURL = documentsURL.appendingPathComponent(fileName)

        return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
    }

NSTemporaryDirectory

    let fileURL = URL(fileURLWithPath:  
    NSTemporaryDirectory()).appendingPathComponent(fileName)
    let destination: DownloadRequest.DownloadFileDestination = { _, _ in
            return (fileURL, [.createIntermediateDirectories, 
.removePreviousFile])
        }