同步将图像上传到Firebase

Question

I am trying to upload a product to Database, and I want all information to be written in one transaction. While this does happen, it doesn't for an uploaded image. This is my code :

let storageRef = Storage.storage().reference().child("ProductsImages").child(product.UniqueID()).child("MainImage.png")
            if let mainChosenImage = self.selectedImageToUpload
            {
                if let uploadData = UIImageJPEGRepresentation(mainChosenImage, 0.2)
                {
                    storageRef.putData(uploadData, metadata: nil)
                    {
                        (StorageMetaData, error) in
                        if error != nil
                        {
                            // MARK - Print error
                            return
                        }

                        self.mainImageURL = StorageMetaData?.downloadURL()?.absoluteString
                        if let urlString = self.mainImageURL
                        {
                            self.ref.child("Products").child(product.UniqueID()).child("MainImage").setValue(urlString)
                            self.ref.child("Users").child(user.uid).child("Products").child(product.UniqueID()).child("MainImage").setValue(urlString)
                            product.AddImageURLToProduct(URL: urlString)
                        }
                    }
                }
            }
            product.RegisterProductOnDatabase(database: self.ref)
            self.performSegue(withIdentifier: "unwindToMyProductsViewController", sender: self)

My code for registering the product:

public func RegisterProductOnDatabase(database dataBase: DatabaseReference)
{
    // Run in one transaction

    let key = dataBase.child("Products").child(self.UniqueID()).key
    let thisProductToRegister : [String:Any] = [
                            "Name": self.Name(),
                            "UniqueID": self.UniqueID(),
                            "Price": self.Price(),
                            "Description": self.Description(),
                            "ToBuy?": self.IsToBuy(),
                            "ToSell?": self.IsToSell(),
                            "Owner": self.m_Owner,
                            "Amount": self.Amount(),
                            "MainImage": self.m_PicturesURLs.first
                          ]

    let childUpdates = ["/Products/\(key)/": thisProductToRegister,
                        "/Users/\(self.m_Owner)/Products/\(key)/": thisProductToRegister]

    dataBase.updateChildValues(childUpdates)

}

I want the complete product to be registered before the segue is performed. How can I do that ?

As of right now, product is registered, segue is performed and product is loaded to CollectionView with default image, then product image is written to Firebase and then loaded to collectionView. I want my product to load with the correct image from the start

Answer 1

The idea is to nest network calls , and in final one perfromSegue

 CallAPI1
  {
     if(sucess)
     {  
            CallAPI2
            {
              if(sucess)
              {  
                  self.performSegue(withIdentifier: "unwindToMyProductsViewController", sender: self)

              }
            }
     }
  }

Answer 2

You want the segue to happen when RegisterProductOnDatabase is finished with its asynchronous calls, so add a parameter to give it its own completion callback, and call it when all the asynchronous work is done:

public func RegisterProductOnDatabase(database dataBase: DatabaseReference, completionHandler: @escaping () -> Void) {

// all your code here

completionHandler()

}

Then call it like this:

product.RegisterProductOnDatabase(database: self.ref, completionHandler: {

self.performSegue(withIdentifier: "unwindToMyProductsViewController", sender: self)
})