How to Focus Accessibility On A Particular Segment in A UISegmentedControl

Question

OK. This answer helps a lot. I can select an accessibility item when a screen is shown. I simply add

UIAccessibility.post(notification: .layoutChanged, argument: <a reference to the UI item to receive focus>)

to the end of my viewWillAppear() method, and the item receives focus.

However, in one of my screens, the item I want to receive focus is a UISegmentedControl, and, when focused, it always selects the first item, no matter which one is selected. Since I followed the excellent suggestion here, I have an accessibility label for each item in the control, and I'd like my focus to begin on whichever segment is selected.

Is there a way to do this? As a rule, I try to avoid "hacky" solutions (like the one I just referenced), but I'm willing to consider anything.

Thanks!

UPDATE: Just to add insult to injury, I am also having an issue with the item I want selected being selected, then a second later, the screen jumps the selection to the first item. That's probably a topic for a second question.

Answer 1

I created a blank project as follows to reproduce the problem:

The solution is taking the selectedIndex to display the selected segment and providing the appropriate segment object for the VoiceOver notification: easy, isn't it?

I naively thought that getting the subview in the segmented control subviews array with the selectedIndex would do the job but that's definitely not possible because the subviews can move inside this array as the following snapshot highlights (red framed first element for instance): The only way to identify a unique segment is its frame, so I pick up the segmented control index and the frame of the selected segment to pass them to the previous view controller.

That will allow to display (index) and read out (frame that identifies the object for the notification) the appropriate selected segment when this screen will appear after the transition.

Hereafter the code snippets for the view controller that contains the 'Next Screen' button:

class SOFSegmentedControl: UIViewController, UpdateSegmentedIndexDelegate {

    var segmentIndex = 0
    var segmentFrame = CGRect.zero


    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if let segueName = segue.identifier {
            if (segueName == "SegmentSegue") {
                if let destVC = segue.destination as? SOFSegmentedControlBis {

                    destVC.delegate = self
                    destVC.segmentIndex = segmentIndex
                    destVC.segmentFrame = segmentFrame
                }
            }
        }
    }


    @IBAction func buttonAction(_ sender: UIButton) { self.performSegue(withIdentifier: "SegmentSegue", sender: sender) }


    func updateSegmentIndex(_ index: Int, withFrame frame: CGRect) {

        segmentIndex = index
        segmentFrame = frame
    }
}

... and for the view controller that displays the segmented control:

protocol UpdateSegmentedIndexDelegate: class { 
    func updateSegmentIndex(_ index: Int, withFrame frame: CGRect) 
}


class SOFSegmentedControlBis: UIViewController {

    @IBOutlet weak var mySegmentedControl: UISegmentedControl!

    var delegate: UpdateSegmentedIndexDelegate?
    var segmentFrame = CGRect.zero
    var segmentIndex = 0
    var segmentFrames = [Int:CGRect]()


    override func viewDidLoad() {
        super.viewDidLoad()

        mySegmentedControl.addTarget(self,
                                     action: #selector(segmentedControlValueChanged(_:)),
                                     for: .valueChanged)

        mySegmentedControl.selectedSegmentIndex = segmentIndex
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        print(mySegmentedControl.subviews)

        let sortedFrames = mySegmentedControl.subviews.sorted(by: { $0.frame.origin.x < $1.frame.origin.x})

        for (index, segment) in sortedFrames.enumerated() { segmentFrames[index] = segment.frame }

        if (self.segmentFrame == CGRect.zero) {
            UIAccessibility.post(notification: .screenChanged,
                                 argument: mySegmentedControl)
        } else {
            mySegmentedControl.subviews.forEach({
                if ($0.frame == self.segmentFrame) {
                    UIAccessibility.post(notification: .screenChanged,
                                         argument: $0)
                }
            })
        }
    }


    @objc func segmentedControlValueChanged(_ notif: NSNotification) {

        delegate?.updateSegmentIndex(mySegmentedControl.selectedSegmentIndex,
                                     withFrame: segmentFrames[mySegmentedControl.selectedSegmentIndex]!) }
    }

The final result is as follows:

1. Double tap to go to the next screen.
2. Select the next element to focus the second segment.
3. Double tap to select the focused element.
4. Get back to the previous screen thanks to the Z gesture natively known by iOS with the navigation controller. The delegate passes the index and the frame of the selected segment.
5. Double tap to go to the next screen.
6. The segment that was formerly selected is read out by VoiceOver and still selected.

You can now Focus Accessibility On A Particular Segment in A UISegmentedControl following this rationale.

I try to avoid "hacky" solutions (like the one I just referenced), but I'm willing to consider anything.

Unfortunately, this solution is a hacky one... sorry. However, it works and I couldn't find another one anywhere else: see it as a personal fix unless you get a cleaner one to share? ;o)

UPDATE... That's probably a topic for a second question.

I can't reproduce the behavior of your update: if you create a dedicated topic for this problem, please add the most detailed code and context so as to provide the most accurate solution.