How to set the button's action from another view controller - ios

Question

how can I create reusable view controller (let's call it "reusableVC") acting like UIAlertController. ReusableVC have "ok" button, that will act depending from where resuableVC called. I know about delegates and NotificationCenter. Just wondering can we pass what "ok" button should do when creating reusableVC, like this:
reusableVC.addAction(UIAlertAction(title: "", style: .default, handler: { (action) in
// some code
}))

Answer 1

If you only need one OK button you may use this solution, otherwise, you can still find interest in this pattern.
class ReusableVC{
var onOKPressed: ( () -> () )?
// Create all your other things and don't forget that you should call onOKPressed() whenever user pushed that OK button
}
class ViewController{
func setupReusableVC(){
let reusableVC = ReusableVC()
reusableVC.onOKPressed = {
print("ok pressed")
}
}
}

Answer 2

The action handler is just a closure. You can declare it everywhere.
In the reusable view controller add a property
var customAction : ((UIAlertAction) -> Void)?
and pass the property as handler
reusableVC.addAction(UIAlertAction(title: "", style: .default, handler: customAction))
In the source view controller create the action
let action : ((UIAlertAction) -> Void)? = { action in
// do something
}
and pass it in perform(segue

Answer 3

Create a UIViewController Extension to include Alert Functionality
extension UIViewController{
open func hideKeyBoardOnTap(){
let tap = UITapGestureRecognizer(target: self, action: #selector(dismissKeyboard))
self.view.addGestureRecognizer(tap)
}
#objc private func dismissKeyboard(){
self.view.endEditing(true)
}
open func showAlertWithOK(_ title: String = "Alert!",message: String = "Please take appropriate action"){
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
let okButton = UIAlertAction(title: "Ok", style: .default, handler:{ (alertAction) in
self.okAction()
})
alert.addAction(okButton)
DispatchQueue.main.async {
self.present(alert, animated: true, completion: nil)
}
}
open func showAlertWithOkAndCancel(_ title: String = "Alert!",_ message: String = "Please take appropriate action", _ firstButtonTitle: String = "Ok", _ firstButtonStyle: UIAlertActionStyle = .default, _ secondButtonTitle: String = "Cancel",_ secondButtonStyle: UIAlertActionStyle = .cancel){
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
let okButton = UIAlertAction(title: firstButtonTitle, style: firstButtonStyle, handler:{ (alertAction) in
self.okAction()
})
let cancelButton = UIAlertAction(title: secondButtonTitle, style: secondButtonStyle, handler: { (alertAction) in
self.cancelAction()
})
alert.addAction(okButton)
alert.addAction(cancelButton)
self.present(alert, animated: true, completion: nil)
}
#objc private func okAction(){
self.dismiss(animated: true, completion: nil)
}
#objc private func cancelAction(){
self.dismiss(animated: true, completion: nil)
}
}
How to Use
func didReceiveError(_ error: CFNetworkErrors) {
var message = error.message
self.showAlertWithOK("Error", message: message)
}
func didEndWebserviceCall() {
self.showAlertWithOK(message: "didEndWebserviceCall")
}
Advantages:
You can access alert using self(which is your viewcontroller in this case)
Code reusability
Clean code.

Answer 4

protocol TapEventDelegate: protocol {
func buttonTap()
}
class ClassWhereDoYouWantToCatchTheEvent: TapEventDelegate {
func buttonTap() {
print("caught!")
}
}
class YourViewControllerClass {
weak var tapEventDelegate: TapEventDelegate?
reusableVC.addAction(UIAlertAction(title: "", style: .default, handler: { (action) in
tapEventDelegate?.buttonTap()
}))
}
to bind your class with YourViewControllerClass and ClassWhereDoYouWantToCatchTheEvent use somewhere at view controller initialization:
classWhereDoYouWantToCatchTheEvent.tapEventHandler = yourViewControllerClass

Answer 5

You can create custom UIViewController class and pass the addAction closure and then you can call that closure on the OK button tap from your CustomAlertController.
final class CustomAlertController: UIViewController {
var actionHandler: (() -> Void)?
lazy var okButton: UIButton = {
let button = UIButton()
button.backgroundColor = .black
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle("OK", for: .normal)
button.addTarget(self, action: #selector(CustomAlertController.didTapOkButton(_:)), for: .touchUpInside)
button.layer.cornerRadius = 10
return button
}()
override func loadView() {
view = UIView()
view.backgroundColor = .white
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
addActionButton()
}
private func addActionButton() {
view.addSubview(okButton)
NSLayoutConstraint.activate([
okButton.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 50),
okButton.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -50),
okButton.heightAnchor.constraint(equalToConstant: 50),
okButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 100)
])
}
public func addAction(title: String, handler: #escaping (() -> Void) {
okButton.setTitle(title, for: .normal)
actionHandler = handler
}
#objc func didTapOkButton(_ button: UIButton) {
actionHandler?()
dismiss(animated: true)
}
}
Then you can present CustomAlertController from your ViewController class and add action like below
class ViewController: UIViewController {
override func loadView() {
view = UIView()
view.backgroundColor = .white
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let alertController = CustomAlertController()
alertController.addAction(title: "OK", handler: { [unowned self] in
self.view.backgroundColor = .blue
print("OK button tapped")
})
present(alertController, animated: true)
}
}