Pass Json response from one Viewcontroller to another Viewcontroller and populate CollectionView

Question

I'm trying to pass a Json response of an Http request from one controller to another, where in the second one I'd like to create a collection view from the recieved data.


import UIKit

class TableViewController: UITableViewController {

    let ingredientList = Ingredients().Ingredients
    public var arrayDrinks: Array<Any> = []
    let session = URLSession.shared


    override func viewDidLoad() {
        super.viewDidLoad()

        self.tableView.reloadData()
        tableView.dataSource = self
        tableView.delegate = self

    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    // MARK: - number of rows
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.ingredientList.count
    }

    // MARK: - creating cell
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cellaIng", for: indexPath)

        let singoloIngrediente = self.ingredientList[indexPath.row]

        cell.textLabel?.text = singoloIngrediente
        return cell
    }


    // MARK: - get the Selected Item
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

        let selectedItem: String = ingredientList[indexPath.row]
        print("The selected ingredient is: \(selectedItem)")

        // parameter for http request
        let param = String(selectedItem.replacingOccurrences(of: " ", with: "_"))

        let url = URL(string: "https://www.thecocktaildb.com/api/json/v1/1/filter.php?i=\(param)")!

        // MARK: - Http request

        let task = session.dataTask(with: url) { data, response, error in

            if error != nil || data == nil {
                print("Client error!")
                return
            }

            guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
                print("Server error!")
                return
            }

            do {
                // data from network request
                let decoder = JSONDecoder()
                let response = try decoder.decode(ObjectDrink.self, from: data!) // ObjectDrink from Model

                self.arrayDrinks.append(response.drinks)
                let destinationVC = DrinksListCollectionViewController()
                destinationVC.remoteArray = response.drinks
                 print("print array drink \(destinationVC.remoteArray)")

            } catch { print(error) }

        }
        performSegue(withIdentifier: "InglistSegue", sender: self)
         task.resume()

//        let destinationVC = DrinksListCollectionViewController()
//        destinationVC.remoteArray = self.arrayDrinks
//        destinationVC.performSegue(withIdentifier: "InglistSegue", sender: self)

    } // END didSelectRowAt

}

When I print the response to the console, the array of the second controller is empty, so no data is passing from the first response (array) to the other controller

Possible duplicate of [Passing Data between View Controllers](https://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) — Yoel Jimenez del valle, Jul 23 '19 at 15:17
that's Obj-c...I've already read other similar questions but I couldn't find how to fix it — SimpleCoder, Jul 23 '19 at 15:29

score 0 · Answer 1 · answered Jul 23 '19 at 15:31

The view controller that you are moving to is not available yet and your line:

let destinationVC = DrinksListCollectionViewController()

Creates a new view controller which is not the one that your app transitions to. To use the view controller that will be shown, you use prepare(for segue: UIStoryboardSegue, sender: Any?) like so:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let destinationVC = segue.destination as? DrinksListCollectionViewController {
        destinationVC.remoteArray = self.arrayDrinks
    }
}

score 0 · Accepted Answer · edited Jul 23 '19 at 15:42

0

You need to present it inside the callback of the URLSession.shared.dataTask like

DispatchQueue.main.async {
    self.arrayDrinks.append(response.drinks)
    let destinationVC = DrinksListCollectionViewController()
    destinationVC.remoteArray = response.drinks
    print("print array drink \(destinationVC.remoteArray)")
    self.present(destinationVC,animated:true,completion:nil)
}

If it's a segue then replace above with ( also inside the completion )

DispatchQueue.main.async {
  performSegue(withIdentifier: "InglistSegue", sender: response.drinks)
}

Add this method

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
  let destinationVC = segue.destination as! DrinksListCollectionViewController 
  destinationVC.remoteArray = sender as! [Model] // model it type of drinks 
}

edited Jul 23 '19 at 15:42

emrcftci

3,355
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answered Jul 23 '19 at 15:33

Shehata Gamal

98,760
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When you segue, you shouldn’t pass your data through the `sender` as it is for the object used to initiate the segue (ex: a UIButton). Pass the actual data to the destination view controller from a variable in the view controller instead. – Nathan Jul 23 '19 at 16:03
@Nathan can you read docs here https://developer.apple.com/documentation/uikit/uiviewcontroller/1621490-prepare for sender , actually it's of type `Any?` and it's widely used for sending the data instead of having to declare a variable , it's up to you as the developer to use it for anything according to your app structure and logic – Shehata Gamal Jul 23 '19 at 16:10

Pass Json response from one Viewcontroller to another Viewcontroller and populate CollectionView

2 Answers2