iOS Refresh Accessibility Label - ios

Question

I have a button with accessibility label #"a". When the button is pressed, I have a callback that sets the accessibility label button.accessibilityLabel = #"b". I know this line of code runs. However, if I tap the button again, VoiceOver still reads a. Unfortunately, the code I'm working with is proprietary, so I can't share it directly.
However, in general, I would like to know what issues might cause VoiceOver to not recognize an update to a label.

Answer 1

THE BEST way to handle dynamic accessibility labels is to override the property functions on the views that are being focused (EX: on a UIButton). This allows TWO things. A: it's a lot easier to maintain than setting the property everywhere it can change. B: you can log information and see when the system is requesting that information, so you can better understand WHY things are happening. So even if it doesn't directly fix your issue, seeing WHEN the system requests your value, and logging that data, is inherently valuable.
Doing this in Objective C
#implementation YourUIButton
-(NSString*)accessibilityLabel {
if(someCondition) {
return #"a";
} else {
return #"b";
}
}
#end
In Swift
public class YourUIButton : UIButton
override public var accessibilityLabel: String? {
get {
if (someCondition) {
return "a"
} else {
return "b"
}
}
set {
NSException.raise(NSException("AccessibilityLabelException", "You should not set this accessibility label.", blah))
}
}
}
You could also use this logic JUST to debug, and allow setting and such.
There are a lot of potential issues here. Race conditions, which view is actually getting focus, is there some parent child relationship going on, etc. Overriding the property and adding logging statements to the above code will help you understand what view is actually getting the accessibility label requested and when. Super valuable information!

Answer 2

Use this while changing button text
UIAccessibility.post(notification: .layoutChanged, argument: yourButton)

Answer 3

Try to add UIAccessibilityTraitUpdatesFrequently to your buttons property accessibilityTraits
- (void)viewDidLoad {
myButton.accessibilityTraits |= UIAccessibilityTraitUpdatesFrequently
}
Also, when changing accessibilityLabel be sure that you're on main thread.
dispatch_async(dispatch_get_main_queue(), ^{
myButton.accessibilityLabel = #"b";
});

Answer 4

You don't really need a way to refresh the voice over labels. Its done automatically. I have tried this and it works as expected.
class ViewController: UIViewController {
var tapCount = 0
var button: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
button = UIButton(type: .system)
button.setTitle("Hello", for: .normal)
button.frame = CGRect(x: 10, y: 10, width: 100, height: 50)
view.addSubview(button)
button.accessibilityLabel = "Hello Button"
button.accessibilityHint = "Tap here to start the action"
button.accessibilityIdentifier = "hello_button"
button.addTarget(self, action: #selector(buttonTap(sender:)), for: .touchUpInside)
}
#IBAction func buttonTap(sender:UIButton) {
tapCount = tapCount + 1
sender.accessibilityLabel = "Hello button, tapped \(tapCount) times"
}
}
What Voice oversays:
Hello Button-pause-Button-pause-Tap here to start the action
On button tap
Hello button, tapped one times
Another tap
Hello button, tapped two times