Upload image to Firebase Synchroniously - ios

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)
})