I have the following Model that returns data to my View Controller:

    func getRecipeSelected(docId: String, completionHandler: @escaping () -> Void) {
        db.collection("recipes").document(docId).getDocument { document, error in
            if let error = error as NSError? {
            }
            else {
                if let document = document {
                    do {
                        self.recipe = try document.data(as: Recipe.self)
                        
                        let recipeFromFirestore = Recipe(
                            id: docId,
                            title: self.recipe!.title ?? "",
                            analyzedInstructions: self.recipe!.analyzedInstructions!)
                        
                        DispatchQueue.main.async {
self.delegateSpecificRecipe?.recipeSpecificRetrieved(recipeSelected: recipeFromFirestore)
                        }
                    }
                    catch {
                        print("Error: \(error)")
                    }
                }
            }
        }
        completionHandler()
    }

And this is in my View Controller:

    var entireRecipe: Recipe? = nil

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
        documentID = recipeDocIdArray[indexPath.row]
        
        model.getRecipeSelected(docId: documentID) {
            print("ISSUE HERE: \(self.entireRecipe)") // FIXME: THIS IS NIL THE FIRST TIME IT IS CALLED
        }
    }

My issue is that entireRecipe isn't assigned the data from the model within the completion handler in my View Controller. If I were to tap the cell for the second time, then the data from the first tap is assigned in that completion handler.

How can I assign the returned data to the entireRecipe within that scope the first time it is tapped?

CodePudding user response：

You are calling delegate method instead of calling completionHandler. And you are also calling delegate method in async block which one called after completionHandler. Don’t need two of them in a row. You can use completionHandler like:

func getRecipeSelected(docId: String, completionHandler: @escaping (Recipe?) -> Void) {
        db.collection("recipes").document(docId).getDocument { document, error in
            if let error = error as NSError? {
            }
            else {
                if let document = document {
                    do {
                        self.recipe = try document.data(as: Recipe.self)
                        
                        let recipeFromFirestore = Recipe(
                            id: docId,
                            title: self.recipe!.title ?? "",
                            analyzedInstructions: self.recipe!.analyzedInstructions!)
                        
                        completionHandler(recipeFromFirestore)
                    }
                    catch {
                        print("Error: \(error)")
                        completionHandler(nil)
                    }
                }
            }
        }
    }

var entireRecipe: Recipe?

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
    documentID = recipeDocIdArray[indexPath.row]
        
    model.getRecipeSelected(docId: documentID) { [weak self] model in
        self?.entireRecipe = model
    }
}