Make variable data type accept all UIViewController subclass-CodePudding

So I have many buttons, maybe up to 12, which is populated from a ForEach loop. And when each one is clicked, the button index will be passed as parameter to a function which will present a new ViewController based on the index of the button.

ForEach(0...11, id: \.self){ index in
    Button {
        openController(index: index)
    }, label: {
        Text("Button \(index)")
    }
}

Now in my openController function, I want to make my code as short as possible. So I will make a switch statement to determine the button clicked and open the respective viewcontroller.

So here's where my question comes in... I want to create just one variable which will be initialized by the respective Viewcontroller. But the problem comes when I declare the variable and try to initialize it.

For instance, since all the ViewControllers are subclasses of the UIViewController, I tried to declare the variable with a UIViewController data type before initializing it

func openController(index: Int){
    var viewController: UIViewController // declaring the variable
    switch index {
        case 0:
            viewController = ZeroViewController
        case 1:
            viewController = OneViewController
        // And it keeps going on till case 11
    }
    self.present(viewController, animated: true)
}

But I will be getting errors if I do that saying that I can't convert viewController which is of UIViewController type to ZeroViewController

So this will make my code bulky, because I'll have to create a variable for every Viewcontroller and also present it differently making my code look like this

func openController(index: Int){
    switch index {
        case 0:
            let viewController = ZeroViewController
            self.present(viewController, animated: true)
        case 1:
            let viewController = OneViewController
            self.present(viewController, animated: true)
        // And it keeps going on till case 11
    }
}

So is that the only option or is there a way I can shorten my code to look like the first function?

CodePudding user response：

Assuming you will also be setting properties in your "destination" view controllers...

If we have these two controllers:

class ZeroViewController: UIViewController {
    var testZero: String = ""
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .red
        print("test Zero:", testZero)
    }
}

class OneViewController: UIViewController {
    var testOne: String = ""
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .blue
        print("test One:", testOne)
    }
}

You can write your func like this:

func openController(index: Int) {
    var vc: UIViewController!
    switch index {
    case 0:
        let viewController = ZeroViewController()
        viewController.testZero = "Hello"
        vc = viewController
    case 1:
        let viewController = OneViewController()
        viewController.testOne = "Goodbye"
        vc = viewController
        // And it keeps going on till case 11
    default:
        return
    }
    self.present(vc, animated: true)
}

So, inside each case:

instantiate a view controller of the specific controller class
set any properties specific to that class
assign a reference to that instance to the vc var
then present vc