Pass data back to previous VC using delegates and

Question

I am trying to pass data BACK to the previous viewController using delegates.

Does anyone know how to pass data back from ViewController B to ViewController A?

So I want to pass data from SecondVC to FirstVC and update custom table view cells with the data from SecondVC 4 address text fields but for some reason, it's not updating at all.

Any help will be much appreciated as I'm just at the beginning level so tried all sorts of things but not able to get it to work.

FirstVC

import UIKit

class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, DataSentDelegate {

    @IBOutlet weak var deliveryAddress: UITableView!

    var customCell: AddressCell = AddressCell()

    override func viewDidLoad() {
        super.viewDidLoad()
        deliveryAddress.delegate = self
        deliveryAddress.dataSource = self
        deliveryAddress.reloadData()
    }

    func userDidEnterData(firstAddress: String, secondAddress: String, cityAddress: String, postcodeAddress: String) {
        customCell.firstLineAddressLbl?.text = firstAddress
        customCell.secondLineAddressLbl?.text = secondAddress
        customCell.cityLineAddressLbl?.text = cityAddress
        customCell.postcodeLineAddressLbl?.text = postcodeAddress
    }

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

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 2
    }



    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
         let cell = tableView.dequeueReusableCell(withIdentifier: "deliveryAddressCell", for: indexPath) as! AddressCell
        cell.updateUI()
        return cell
    }
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 165
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "addDeliveryAddressVC" {
            let addDestination:AddingDestinationVC = segue.destination as! AddingDestinationVC
            addDestination.delegate = self
    }


}

}

SecondVC

import UIKit

protocol DataSentDelegate {
    func userDidEnterData(firstAddress: String, secondAddress: String, cityAddress: String, postcodeAddress: String)
}

class AddingDestinationVC: UIViewController {

    @IBOutlet weak var firstLineAddressTextField: UITextField!
    @IBOutlet weak var secondLineAddressTextField: UITextField!
    @IBOutlet weak var cityLineAddressTextField: UITextField!
    @IBOutlet weak var postcodeLineAddressTextField: UITextField!

    var delegate: DataSentDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    @IBAction func addBtnWasPressed(_ sender: Any) {
        if delegate != nil {
            if firstLineAddressTextField.text != nil {
                 let firstLineAddress = firstLineAddressTextField.text
                print(firstLineAddress as Any)
                let secondLineAddress = secondLineAddressTextField.text
                let cityLineAddress = secondLineAddressTextField.text
                let postcodeLineAddress = postcodeLineAddressTextField.text
                delegate?.userDidEnterData(firstAddress: firstLineAddress!, secondAddress: secondLineAddress!, cityAddress: cityLineAddress!, postcodeAddress: postcodeLineAddress!)
                navigationController?.popViewController(animated: true)
        }
    }

}
}

CustomCell

import UIKit

class AddressCell: UITableViewCell {

    @IBOutlet weak var firstLineAddressLbl: UILabel!
    @IBOutlet weak var secondLineAddressLbl: UILabel!
    @IBOutlet weak var cityLineAddressLbl: UILabel!
    @IBOutlet weak var postcodeLineAddressLbl: UILabel!
    @IBOutlet weak var numberLbl: UILabel!
    @IBOutlet weak var startBtn: UIButton!
    @IBOutlet weak var distanceLbl: UILabel!
    @IBOutlet weak var metricLbl: UILabel!

    func updateUI() {
        DeliveryDestinations(FirstLineAddress: firstLineAddressLbl.text, SecondLineAddress: secondLineAddressLbl.text, CityLineAddress: cityLineAddressLbl.text, PostCodeLineAddress: postcodeLineAddressLbl.text)
    }

}

Model file

import Foundation

struct DeliveryDestinations {
    var FirstLineAddress: String?
    var SecondLineAddress: String?
    var CityLineAddress: String?
    var PostcodeLineAddress: String?

    init(FirstLineAddress: String? , SecondLineAddress: String?, CityLineAddress: String?, PostCodeLineAddress: String?) {
        self.FirstLineAddress = FirstLineAddress
        self.SecondLineAddress = SecondLineAddress
        self.CityLineAddress = CityLineAddress
        self.PostcodeLineAddress = PostCodeLineAddress
    }

}

Answer 1

Check below corrected code:

MainVC:

import UIKit

class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, DataSentDelegate {

    @IBOutlet weak var deliveryAddress: UITableView!

    //Create array which will return your address data
    var addressArr = [DeliveryDestinations]()

    override func viewDidLoad() {
        super.viewDidLoad()
        deliveryAddress.delegate = self
        deliveryAddress.dataSource = self
        deliveryAddress.reloadData()
    }

    //add parameter for created address object
    func userDidEnterData(addressObj: DeliveryDestinations) {

        //append added object into your table array
        self.addressArr.append(addressObj)
        //Reload your tableview once your new object added.
        self.deliveryAddress.reloadData()
    }

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

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        //change this with array count
        return addressArr.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "deliveryAddressCell", for: indexPath) as! AddressCell

        //get address object from array which you can assign to cell
        let addressObj = addressArr[indexPath.row]
        //assign data from array
        cell.updateUI(addressObj: addressObj)
        return cell
    }

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 165
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "addDeliveryAddressVC" {
            let addDestination:AddingDestinationVC = segue.destination as! AddingDestinationVC
            addDestination.delegate = self
        }
    }
}

AddingDestinationVC:

import UIKit

protocol DataSentDelegate {
    //Replace parameter with DeliveryDestinations
    func userDidEnterData(addressObj: DeliveryDestinations)
}

class AddingDestinationVC: UIViewController {

    @IBOutlet weak var firstLineAddressTextField: UITextField!
    @IBOutlet weak var secondLineAddressTextField: UITextField!
    @IBOutlet weak var cityLineAddressTextField: UITextField!
    @IBOutlet weak var postcodeLineAddressTextField: UITextField!

    var delegate: DataSentDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    @IBAction func addBtnWasPressed(_ sender: Any) {
        if delegate != nil {
            if firstLineAddressTextField.text != nil {

                //Create Model object DeliveryDestinations
                let addressObj = DeliveryDestinations(FirstLineAddress: firstLineAddressTextField.text, SecondLineAddress: secondLineAddressTextField.text, CityLineAddress: cityLineAddressTextField.text, PostCodeLineAddress: postcodeLineAddressTextField.text)
                //add that object to previous view with delegate
                delegate?.userDidEnterData(addressObj: addressObj)
                navigationController?.popViewController(animated: true)
            }
        }
    }
}

AddressCell:

class AddressCell: UITableViewCell {

    @IBOutlet weak var firstLineAddressLbl: UILabel!
    @IBOutlet weak var secondLineAddressLbl: UILabel!
    @IBOutlet weak var cityLineAddressLbl: UILabel!
    @IBOutlet weak var postcodeLineAddressLbl: UILabel!
    @IBOutlet weak var numberLbl: UILabel!
    @IBOutlet weak var startBtn: UIButton!
    @IBOutlet weak var distanceLbl: UILabel!
    @IBOutlet weak var metricLbl: UILabel!

    func updateUI(addressObj: DeliveryDestinations) {

        //Drow your cell with values from addressObj
        firstLineAddressLbl.text = addressObj.FirstLineAddress
        secondLineAddressLbl.text = addressObj.SecondLineAddress
        cityLineAddressLbl.text = addressObj.CityLineAddress
        postcodeLineAddressLbl.text = addressObj.PostcodeLineAddress
    }
}

And your result will be:

And here is your updated code.

Answer 2

Maintain an array that contains the data.

//In your MainVC
var deliveryDestinationDataArray =  [DeliveryDestinations]()

IN delegate method, you need to save data to the data source.

func userDidEnterData(firstAddress: String, secondAddress: String, cityAddress: String, postcodeAddress: String) {
    let deliveryDestinationData = DeliveryDestinations(FirstLineAddress: firstAddress, SecondLineAddress: secondAddress, CityLineAddress: cityAddress, PostCodeLineAddress: postcodeAddress)
    deliveryDestinationDataArray.append(deliveryDestinationData)
}

In cellForRowAtIndexPath

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
     let cell = tableView.dequeueReusableCell(withIdentifier: "deliveryAddressCell", for: indexPath) as! AddressCell
   cell.updateUI(deliveryDestinationData:deliveryDestinationDataArray[indexPath.row])
    return cell
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    //change count with deliveryDestinationDataArray count
    return deliveryDestinationDataArray.count
}

Update your cell with data

 func updateUI(with dataModel: DeliveryDestinations) {
    firstLineAddressLbl.text = dataModel.FirstLineAddress
    secondLineAddressLbl.text = dataModel.SecondLineAddress
    cityLineAddressLbl.text = dataModel.CityLineAddress
    postcodeLineAddressLbl.text = dataModel.PostcodeLineAddress
}

Now in viewWillAppear, you need to reload the tableview.

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    deliveryAddress.reloadData()
}

Answer 3

Replace your FirstVC with following lines of code:

    import UIKit

class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, DataSentDelegate {
@IBOutlet weak var deliveryAddress: UITableView!

var dataModels: [DeliveryDestinations] = [DeliveryDestinations]()

override func viewDidLoad() {
    super.viewDidLoad()
    deliveryAddress.delegate = self
    deliveryAddress.dataSource = self
    deliveryAddress.reloadData()
}

func userDidEnterData(firstAddress: String, secondAddress: String, cityAddress: String, postcodeAddress: String) {
    let newEntry: DeliveryDestinations = DeliveryDestinations(FirstLineAddress: firstAddress, SecondLineAddress: secondAddress, CityLineAddress: cityAddress, PostCodeLineAddress: postcodeAddress)
     dataModels.append(newEntry)
     deliveryAddress.reloadData()
}

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

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return dataModels.count()
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
     let cell = tableView.dequeueReusableCell(withIdentifier: "deliveryAddressCell", for: indexPath) as! AddressCell
      let dataModel = dataModels[indexPath.row]
    cell.updateUI(with: dataModel)
    return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 165
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "addDeliveryAddressVC" {
        let addDestination:AddingDestinationVC = segue.destination as! AddingDestinationVC
        addDestination.delegate = self
}

}

and Custom cell class with :

import UIKit

class AddressCell: UITableViewCell {

    @IBOutlet weak var firstLineAddressLbl: UILabel!
    @IBOutlet weak var secondLineAddressLbl: UILabel!
    @IBOutlet weak var cityLineAddressLbl: UILabel!
    @IBOutlet weak var postcodeLineAddressLbl: UILabel!
    @IBOutlet weak var numberLbl: UILabel!
    @IBOutlet weak var startBtn: UIButton!
    @IBOutlet weak var distanceLbl: UILabel!
    @IBOutlet weak var metricLbl: UILabel!

    func updateUI(with dataModel: DeliveryDestinations) {
        firstLineAddressLbl.text = dataModel.FirstLineAddress
        secondLineAddressLbl.text = dataModel.SecondLineAddress
        cityLineAddressLbl.text = dataModel.CityLineAddress
        postcodeLineAddressLbl.text = dataModel.PostcodeLineAddress
    }

}

Also, you should declare your property names in camel case format.