Show UIView When Popping Back on a Navigation Controller - ios

Question

So I'm trying to show an UIView in a stack view when I click continue on a controller and pop back to the previous controller. However, I'm having trouble showing the view when I pop. It will show if I present the controller, but I need it to show when I pop. How should I go about this? Thank you.
// ServiceDetailController
// MARK: - Properties
lazy var dateContainer: ShadowCardView = {
let view = ShadowCardView()
view.backgroundColor = .white
view.addShadow()
view.setHeight(height: 40)
let stack = UIStackView(arrangedSubviews: [calendarIcon, dateLabel, timeOfDayLabel])
stack.axis = .horizontal
stack.distribution = .fillProportionally
stack.spacing = 8
view.addSubview(stack)
stack.centerY(inView: view)
stack.anchor(left: view.leftAnchor, right: view.rightAnchor, paddingLeft: 12, paddingRight: 70)
view.addSubview(closeButton)
closeButton.centerY(inView: view)
closeButton.anchor(right: view.rightAnchor, paddingRight: 12)
return view
}()
lazy var dateStack = UIStackView(arrangedSubviews: [dateLabelStack, dateContainer, dateContainerView])
// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
configureUI()
}
// MARK: - Selectors
#objc func handleDateCreationTapped() {
let controller = DateCreationController()
controller.jobService = self.jobService
navigationController?.pushViewController(controller, animated: true)
}
// MARK: - Helper Functions
fileprivate func configureUI() {
setupNavigationBar()
view.backgroundColor = .groupTableViewBackground
setupServiceInfoView()
setupFormView()
}
fileprivate func setupFormView() {
showDataContainer(shouldShow: false)
setupTapGestureRecognizers()
}
fileprivate func setupTapGestureRecognizers() {
let dateTap = UITapGestureRecognizer(target: self, action: #selector(handleDateCreationTapped))
dateTap.numberOfTapsRequired = 1
dateTextField.addGestureRecognizer(dateTap)
}
func showDateContainer(shouldShow: Bool) {
if shouldShow {
dateContainer.isHidden = false
dateStack.spacing = 5
} else {
dateContainer.isHidden = true
dateStack.spacing = -18
}
}
// DateCreationController
// MARK: - Properties
private let continueButton: UIButton = {
let button = UIButton(type: .system)
button.setTitle("Continue", for: .normal)
button.setTitleColor(.white, for: .normal)
button.titleLabel?.font = UIFont(name: "AvenirNext-Medium", size: 14)
button.backgroundColor = .darkGray
button.setHeight(height: 50)
button.layer.cornerRadius = 8
button.addTarget(self, action: #selector(handleContinue), for: .touchUpInside)
return button
}()
// MARK: - Selectors
#objc func handleContinue() {
let controller = ServiceDetailController()
controller.showDateContainer(shouldShow: true)
navigationController?.popViewController(animated: true)
}

Answer 1

The main problem is this func in your DateCreationController:
#objc func handleContinue() {
// here, you are creating a NEW instance of ServiceDetailController
let controller = ServiceDetailController()
controller.showDateContainer(shouldShow: true)
// here, you are popping back to where you came from... the EXISTING instance of ServiceDetailController
navigationController?.popViewController(animated: true)
}
You need to use either delegate/protocol pattern or a closure.
Here's an example using a closure...
Add this var to your DateCreationController class:
var continueCallback: ((Bool)->())?
In your ServiceDetailController class, when you instantiate and push your DateCreationController, you'll also setup that closure:
#objc func handleDateCreationTapped() {
let controller = DateCreationController()
controller.jobService = self.jobService
// add the closure
controller.continueCallback = { [weak self] shouldShow in
guard let self = self else { return }
self.showDateContainer(shouldShow: shouldShow)
self.navigationController?.popViewController(animated: true)
}
navigationController?.pushViewController(controller, animated: true)
}
Then, in your button action in DateCreationController, you "call back" using that closure:
#objc func handleContinue() {
continueCallback?(true)
}
Here's a runnable example. It creates a simple yellow view as the dateContainer view, but it is hidden on load. Tapping anywhere will push to DateCreationController, which has a single "Continue" button. Tapping that button will execute the closure, where the dateContainer view will be set to visible and we'll pop back:
class ServiceDetailController: UIViewController {
var jobService: String = "abc"
// plain yellow view
let dateContainer: UIView = {
let view = UIView()
view.backgroundColor = .yellow
return view
}()
// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
let infoLabel = UILabel()
infoLabel.text = "Tap anywhere"
view.addSubview(infoLabel)
view.addSubview(dateContainer)
infoLabel.translatesAutoresizingMaskIntoConstraints = false
dateContainer.translatesAutoresizingMaskIntoConstraints = false
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
infoLabel.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
infoLabel.centerXAnchor.constraint(equalTo: g.centerXAnchor),
dateContainer.topAnchor.constraint(equalTo: infoLabel.bottomAnchor, constant: 20.0),
dateContainer.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
dateContainer.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
dateContainer.heightAnchor.constraint(equalToConstant: 100.0),
])
setupTapGestureRecognizers()
// hide dateContainer on load
showDateContainer(shouldShow: false)
}
// MARK: - Selectors
#objc func handleDateCreationTapped() {
let controller = DateCreationController()
controller.jobService = self.jobService
// add the closure
controller.continueCallback = { [weak self] shouldShow in
guard let self = self else { return }
self.showDateContainer(shouldShow: shouldShow)
self.navigationController?.popViewController(animated: true)
}
navigationController?.pushViewController(controller, animated: true)
}
// MARK: - Helper Functions
fileprivate func setupTapGestureRecognizers() {
let dateTap = UITapGestureRecognizer(target: self, action: #selector(handleDateCreationTapped))
dateTap.numberOfTapsRequired = 1
view.addGestureRecognizer(dateTap)
}
func showDateContainer(shouldShow: Bool) {
if shouldShow {
dateContainer.isHidden = false
} else {
dateContainer.isHidden = true
}
}
}
class DateCreationController: UIViewController {
var jobService: String = "abc"
var continueCallback: ((Bool)->())?
lazy var continueButton: UIButton = {
let button = UIButton(type: .system)
button.setTitle("Continue", for: .normal)
button.setTitleColor(.white, for: .normal)
button.titleLabel?.font = UIFont(name: "AvenirNext-Medium", size: 14)
button.backgroundColor = .darkGray
button.layer.cornerRadius = 8
button.addTarget(self, action: #selector(handleContinue), for: .touchUpInside)
return button
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .green
view.addSubview(continueButton)
continueButton.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
continueButton.centerXAnchor.constraint(equalTo: view.centerXAnchor),
continueButton.centerYAnchor.constraint(equalTo: view.centerYAnchor),
continueButton.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.75),
continueButton.heightAnchor.constraint(equalToConstant: 50.0),
])
}
// MARK: - Selectors
#objc func handleContinue() {
continueCallback?(true)
}
}