下載圖像，然后從Firebase Swift 3緩存它

Question

我目前正在嘗試設置用戶個人資料圖片。 我讓用戶拍攝上載到Firebase的圖像，但是我想下載該圖像並將其緩存。 我現在無法下載它，在解決該問題之后，我將擔心對其進行緩存。

 // 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())")
        }

    }

現在，我在問題導航器中遇到了什么問題：

在reference = self.storage上存在此問題。 先感謝您！

//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

存儲未聲明為類的屬性，而是在該方法中聲明的。 此外，即使已將其聲明為類的屬性，也可以迅速將自己置於類屬性之前，除非您處於閉包內。

要么做：

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
  }
}

或者，理想情況下，重組代碼：

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將識別當前用戶的圖像，否則我們應該將profileimageurl保存在數據庫中