Using a UISegmentedControl like a UISwitch

Question

Is it possible to use a UISegmentedControl with 3 segments as if it was a three-way UISwitch? I tried to use one as a currency selector in the settings section of my app with no luck, it keeps reseting to the first segment when I switch views and that creates a big mess.

I proceeded like that:

IBAction func currencySelection(_ sender: Any) {
    switch segmentedControl.selectedSegmentIndex {
    case 0:
        WalletViewController.currencyUSD = true
        WalletViewController.currencyEUR = false
        WalletViewController.currencyGBP = false
        MainViewController().refreshPrices()
        print(0)
    case 1:
        WalletViewController.currencyUSD = false
        WalletViewController.currencyEUR = true
        WalletViewController.currencyGBP = false
        MainViewController().refreshPrices()
        print(1)
    case 2:
        WalletViewController.currencyUSD = false
        WalletViewController.currencyEUR = false
        WalletViewController.currencyGBP = true
        MainViewController().refreshPrices()
        print(2)
    default:
        break
    }
}

Answer 1

The UISegmentedControl is implemented in the SettingsViewController of the app to choose between currencies to display in the MainViewController.

(Taken from a comment in @pacification's answer.)

This was the missing piece I was looking for. It provides a lot of context.

TL;DR;

Yes, you can use a three segment UISegmentedControl as a three-way switch. The only real requirement is that you can have only one value or state selected.

But I wasn't grasping why your code referred to two view controllers and some of switching views resulting in resetting the segment. One very good way to do what you want is to:

• Have MainViewController present SettingsViewController. Presenting it modally means the user is only doing one thing at a time. When they are making setting changes, you do not want them adding new currency values.

• Create a delegate protocol in SettingsViewController and make MainViewController conform to it. This tightly-couples changes made to the settings to the view controller interested in what those changes are.

Here's a template for what I'm talking about:

SettingsViewController:

protocol SettingsVCDelegate {
    func currencyChanged(sender: SettingsViewController)
}
class SettingsViewController : UIViewController {

    var delegate:SettingsVCDelegate! = nil
    var currency:Int = 0    
    @IBAction func valueChanged(_ sender: UISegmentedControl) {
        currency = sender.selectSegmentIndex
        delegate.currencyChanged(sender:self)
    }
}

MainViewController:

class MainViewController: UIViewController, SettingsVCDelegate {
    var currency:Int = 0
    let settingsVC = SettingsViewController()
    override func viewDidLoad() {
        super.viewDidLoad()
        settingsVC.delegate = self
    }
    func presentSettings() {
        present(settingsVC, animated: true, completion: nil)
    }
    func currencyChanged(sender:SettingsViewController) {
        currency = sender.currency
    }
}

You can also create an enum of type Int to make your code more readable, naming each value as currencyUSD, currencyEUR, and currencyGBP. I'll leave that to you as a learning exercise.