下载图像，然后从Firebase Swift 3缓存它

Question

I'm currently trying to setup a user profile picture. I have the User takes an image which is uploaded to Firebase, but I want to download that image and cache it. I'm having problems with downloading it right now, after I get that fixed I will worry about caching it.

 // Uploading Images to Firebase
func uploadImageToFirebaseStorage(data: NSData ) {
    let storageRef = FIRStorage.storage().reference(withPath: "myPics/profilePic.jpg")
    let uploadMetaData = FIRStorageMetadata()
    uploadMetaData.contentType = "image/jpeg"
    let uploadTask = storageRef.put(data as Data, metadata: uploadMetaData) { (metadata, error) in
        if (error != nil) {
            print("I Received an error \(error?.localizedDescription)")
        } else {
            print("Upload Complete! Here is the MetaData \(metadata?.downloadURL())")
        }

    }

Now what I'm having problems with the Issue Navigator:

It has this issue on reference = self.storage . Thank you in advance!

//Download Image for User Profile Picture
func downloadImageUserFromFirebase() {
    let storage = FIRStorage.storage()
    var reference: FIRStorageReference!
        reference = self.storage.referenceForURL("gs:URL.appspot.com")
        reference.downloadURL { (url, error) in
    let data = NSData(contentsOf: url!)
    let image = UIImage(data: data! as Data)
    self.profileImageView.image = image
    }
    }

Answer 1

Storage wasn't declared as a property of the class, it was declared within that method. Additionally, even if it was declared as a property of the class, in swift you don't need to put self before a class property any longer unless you are within a closure.

Either do:

func downloadImageUserFromFirebase() {
  let storage = FIRStorage.storage()
  var reference: FIRStorageReference!
  //all I did here was remove self before storage
  reference = storage.referenceForURL("gs:URL.appspot.com")
  reference.downloadURL { (url, error) in
    let data = NSData(contentsOf: url!)
    let image = UIImage(data: data! as Data)
    self.profileImageView.image = image
  }
}

Or, ideally, restructure the code:

class ProfileViewController: UIViewController {

  //here we are initializing it as a property of the class
  let storage = FIRStorage.storage()

  func downloadImageUserFromFirebase() {
    var reference: FIRStorageReference = storage.referenceForURL("gs:URL.appspot.com")
    reference.downloadURL { (url, error) in
      //using a guard statement to unwrap the url and check for error
      guard let imageURL = url, error == nil {
        //handle error here if returned url is bad or there is error
        return
      }
      guard let data = NSData(contentsOf: imageURL) else {
        //same thing here, handle failed data download
        return
      }
      let image = UIImage(data: data)
      self.profileImageView.image = image
    }
  }

}

Answer 2

reference.downloadurl将识别当前用户的图像，否则我们应该将profileimageurl保存在数据库中