Focus_in_tvOS

ViewController.swift

import UIKit

class ViewController: UIViewController {

    @IBOutlet var buttonA:UIButton!
    @IBOutlet var buttonB:UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        let focusGuide = UIFocusGuide()
        focusGuide.preferredFocusedView = buttonB
        view.addLayoutGuide(focusGuide)

        view.addConstraint(NSLayoutConstraint(item: focusGuide,
            attribute: .Width,
            relatedBy: .Equal,
            toItem: buttonA,
            attribute: .Width,
            multiplier: 1,
            constant: 0))
        view.addConstraint(NSLayoutConstraint(item: focusGuide,
            attribute: .Height,
            relatedBy: .Equal,
            toItem: buttonA,
            attribute: .Height,
            multiplier: 1,
            constant: 0))
        view.addConstraint(NSLayoutConstraint(item: focusGuide,
            attribute: .CenterX,
            relatedBy: .Equal,
            toItem: buttonB,
            attribute: .CenterX,
            multiplier: 1,
            constant: 0))
        view.addConstraint(NSLayoutConstraint(item: focusGuide,
            attribute: .CenterY,
            relatedBy: .Equal,
            toItem: buttonA,
            attribute: .CenterY,
            multiplier: 1,
            constant: 0))
    }

    //MARK: - UIFocusEnvironment

    override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
        //TODO: update the 'preferredFocusView' of our focusGuide depending on which view is now in focus
    }
}