从Firebase快照URL显示图像的问题

Question

我正在尝试从UIImageView中存储在Firebase数据库中的URL中显示图像。该路径返回正确的URL（我可以在控制台中看到它）；但是，该图像不会出现在连接的图像视图中。有什么建议么？

let imgRef = Database.database().reference(fromURL: "https://ryan-915d2.firebaseio.com/")
        imgRef.child("locations")
              .child("111 Smith Street")
              .child("building ")
              .child("image")
              .observeSingleEvent(of: .value, with: { snapshot in

            if let url = snapshot.value as? String {
                print(snapshot, "I found the image")
                URLSession.shared.dataTask(with: URL(string: url)!) { data, response, error in
                    if error == nil {
                        let image = UIImage(data: data!)
                        DispatchQueue.main.async {
                        self.imageView.image = image
                        }
                    }
                }.resume()
        }
     }
  )}

}