Alamofire在put请求中下载请求？

Question

我有一个功能可以处理将用户选择的照片上传到Firebase，然后获取代码可以查找图片的网址。

不使用Alamofire，此代码完成了这项工作：

func uploadToFirebase() {
    AppDelegate.instance().showActivityIndicator()

    let uid = FIRAuth.auth()!.currentUser!.uid
    let ref = FIRDatabase.database().reference()
    let storage = FIRStorage.storage().reference(forURL: "gs://cloudcamerattt.appspot.com")
    let key = ref.child("posts").childByAutoId().key
    let imageRef = storage.child("posts").child(uid).child("\(key).jpg")
    let data = UIImageJPEGRepresentation(self.previewImage.image!, 0.6)

    let uploadTask = imageRef.put(data!, metadata: nil) { (metadata, error) in
        if error != nil {
            print(error!.localizedDescription)
            AppDelegate.instance().dismissActivityIndicator()
            return
        }

        imageRef.downloadURL(completion: { (url, error) in

            if let url = url {
                let feed = ["userID" : uid,
                            "pathToImage" : url.absoluteString,
                            "likes" : 0,
                            "poster" : FIRAuth.auth()!.currentUser!.displayName!,
                            "postID" : key] as [String : Any]

                let postFeed = ["\(key)" : feed]
                ref.child("posts").updateChildValues(postFeed)
                AppDelegate.instance().dismissActivityIndicator()

                let feedController = self.storyboard?.instantiateViewController(withIdentifier: "feedVC") as! FeedViewController
                feedController.navigationItem.setHidesBackButton(true, animated: false)

                self.tabBarController?.selectedIndex = 0
            }
        })
    }
    uploadTask.resume()
}

现在我正试图通过使用Alamofire来清理它：

func uploadToFirebase() {
    AppDelegate.instance().showActivityIndicator()

    let uid = FIRAuth.auth()!.currentUser!.uid
    let ref = FIRDatabase.database().reference()
    let storage = FIRStorage.storage().reference(forURL: "gs://cloudcamerattt.appspot.com")
    let key = ref.child("posts").childByAutoId().key
    let imageRef = storage.child("posts").child(uid).child("\(key).jpg")
    let data = UIImageJPEGRepresentation(self.previewImage.image!, 0.6)

    let putRequest = Alamofire.request("gs://cloudcamerattt.appspot.com", method: .put)
    putRequest.responseData { (data) in

        imageRef.downloadURL(completion: { (url, error) in

            if let url = url {
                let feed = ["userID" : uid,
                            "pathToImage" : url.absoluteString,
                            "likes" : 0,
                            "poster" : FIRAuth.auth()!.currentUser!.displayName!,
                            "postID" : key] as [String : Any]

                let postFeed = ["\(key)" : feed]
                ref.child("posts").updateChildValues(postFeed)
                AppDelegate.instance().dismissActivityIndicator()

                let feedController = self.storyboard?.instantiateViewController(withIdentifier: "feedVC") as! FeedViewController
                feedController.navigationItem.setHidesBackButton(true, animated: false)

                self.tabBarController?.selectedIndex = 0
            }
        })
    }
}

现在我不确定如何使用Alamofire来获取网址而不是imageRef.downloadURL(completion: { (url, error) in。 Alamofire下载功能都没有完成处理程序，说实话，我不完全确定如何在这种情况下实现它，不管是Alamofire的新手。

有没有办法与Alamofire一起完成这项特殊任务？或者我必须以不同方式执行整个任务吗？