A UITabBarController subclass that allows navigating between tabs using cmd+number on a hardware keyboard.

KeyboardTabBarController.swift

// Douglas Hill, May 2019
// Find the latest version of this file at https://github.com/douglashill/KeyboardKit

import UIKit

/// A tab bar controller that allows navigating between tabs using cmd+number on a hardware keyboard.
/// So cmd+1 for the first tab, cmd+2 for the second tab etc.
public class KeyboardTabBarController: UITabBarController {

    public override var keyCommands: [UIKeyCommand]? {
        var commands = super.keyCommands ?? []

        if let items = tabBar.items {
            commands += items.enumerated().map { index, tabBarItem in
                UIKeyCommand(maybeTitle: tabBarItem.title, action: #selector(scrollToNumberedTab), input: String(index + 1), modifierFlags: .command)
            }
        }

        return commands
    }

    // For using command-1 to command-9.
    @objc private func scrollToNumberedTab(_ sender: UIKeyCommand) {
        guard let keyInput = sender.input, let targetTabNumber = Int(keyInput), targetTabNumber > 0 else {
            return
        }

        selectedIndex = targetTabNumber - 1
    }
}

private extension UIKeyCommand {
    /// Makes the title optional compared to the UIKit method.
    convenience init(maybeTitle: String?, action: Selector, input: String, modifierFlags: UIKeyModifierFlags) {
        if let title = maybeTitle {
            if #available(iOS 13, *) {
                self.init(title: title, action: action, input: input, modifierFlags: modifierFlags)
            } else {
                self.init(input: input, modifierFlags: modifierFlags, action: action, discoverabilityTitle: title)
            }
        } else {
            self.init(input: input, modifierFlags: modifierFlags, action: action)
        }
    }
}