iOS (Swift): Protocol for UIViewController that adds a new object

Question

I have a view controller that is responsible for adding a new object, say a new contact. This view controller ( AddContactViewController ) has the following UIBarButtonItem on a UINavigationBar , which is starts of disabled until enough information is provided to enable it. Then when this button is pressed a method ( doneButtonPressed ) is called.

The layout is as follows:

class AddContactViewController: UIViewController {

    @IBOutlet weak var doneButton: UIBarButtonItem! {
        didSet {
            doneButton.isEnabled = false
            doneButton.target = self
            doneButton.action = #selector(self.doneButtonPressed)
        }
    }

     @objc fileprivate func doneButtonPressed() {
         // do some stuff ...
         self.dismiss(animated: false, completion: nil)
     }

}

As this is quite a common thing to have and there's a lot of boiler plate code, I've been working on a protocol AddingHandler but haven't quite worked out how to have UIBarButtonItem as a weak variable which hooks up to a storboard or if this is even the right way to go.

protocol AddingHandler {
    var doneButton: UIBarButtonItem? { get set }
    func doneButtonPressed()
}

extension protocol where Self: UIViewController {
    func configureDoneButton() {
        doneButton.isEnabled = false
        doneButton.target = self
        doneButton.action = #selector(self.doneButtonPressed)        
    }
}

Any help or comments in making this work would be much appreciated.

The problem How is best to add a weak UIButton to a protocol which can then be hooked up in a story board where UIViewController implements it? As there is a lot of repetitive code here should I wish to have another AddSomethingViewController I was wondering if there was a neater way of only writing this once (in a protocol with an extension) then calling the protocol in any view controller that is adding something new ...

Answer 1

You can simply configure the doneButton in viewDidLoad()

override func viewDidLoad()
{
    super.viewDidLoad()
    doneButton.isEnabled = false
    doneButton.target = self
    doneButton.action = #selector(self.doneButtonPressed)
}

Edit 1:

@objc protocol AddingHandler
{
    var doneButton: UIBarButtonItem? { get }
    @objc func doneButtonPressed()
}

extension AddingHandler where Self: UIViewController
{
    func configureDoneButton()
    {
        doneButton?.isEnabled = false
        doneButton?.target = self
        doneButton?.action = #selector(doneButtonPressed)
    }
}

class AddContactViewController: UIViewController, AddingHandler
{
    @IBOutlet weak var doneButton: UIBarButtonItem!

    override func viewDidLoad()
    {
        super.viewDidLoad()
        configureDoneButton()
    }

    func doneButtonPressed()
    {
        // do some stuff ...
        self.dismiss(animated: false, completion: nil)
    }
}

I've used ObjC runtime to resolve the issue. Try implementing it at your end and check if it works for you.