How can I determine the index path for the currently focused UITableViewCell using Voice Over? - ios

Question

I have a dynamic UITableView. For each cell, I add a UIAccessibilityCustomAction. When the action fires, I need to know the index path so I can respond accordingly and update my model.
In tableView(_:cellForRowAt:) I add my UIAccessibilityCustomAction like this...
cell.accessibilityCustomActions = [
UIAccessibilityCustomAction(
name: "Really Bad Name",
target: self,
selector: #selector(doSomething)
)
]
I have tried to use UIAccessibility.focusedElement to no avail...
#objc private func doSomething() {
let focusedCell = UIAccessibility.focusedElement(using: UIAccessibility.AssistiveTechnologyIdentifier.notificationVoiceOver) as! UITableViewCell
// Do something with the cell, like find the indexPath.
}
The problem is that casting to a cell fails. The debugger says that the return value type is actually a UITableTextAccessibilityElement, which I could find no information on.

Answer 1

When the action fires, I need to know the index path so I can respond accordingly and update my model.
The best way to reach your goal is to use the UIAccessibilityFocus informal protocol methods by overriding them in your object directly (the table view cell class in your case): you'll be able to catch the needed index path when a custom action is fired.
I suggest to take a look at this answer dealing with catching accessibility focus changed that contains a detailed solution with code snippets if need be.😉
Example snippet...
class SomeCell: UITableViewCell
override open func accessibilityElementDidBecomeFocused() {
// Notify view controller however you want (delegation, closure, etc.)
}
}

Answer 2

I ended up having to solve this myself to bodge an Apple bug. You've likely solved this problem, but this is an option similar to your first suggestion.
func accessibilityCurrentlySelectedIndexPath() -> IndexPath? {
let focusedElement:Any
if let voiceOverObject = UIAccessibility.focusedElement(using: UIAccessibility.AssistiveTechnologyIdentifier.notificationVoiceOver) {
focusedElement = voiceOverObject
} else if let switchControlObject = UIAccessibility.focusedElement(using: UIAccessibility.AssistiveTechnologyIdentifier.notificationSwitchControl) {
focusedElement = switchControlObject
} else {
return nil
}
let accessibilityScreenFrame:CGRect
if let view = focusedElement as? UIView {
accessibilityScreenFrame = view.accessibilityFrame
} else if let accessibilityElement = focusedElement as? UIAccessibilityElement {
accessibilityScreenFrame = accessibilityElement.accessibilityFrame
} else {
return nil
}
let tableViewPoint = UIApplication.shared.keyWindow!.convert(accessibilityScreenFrame.origin, to: tableView)
return tableView.indexPathForRow(at: tableViewPoint)
}
What we're essentially doing here is getting the focused rect (in screen coordinates) and then translating it back to the table view's coordinate space. We can then ask the table view for the indexpath which contains that point. Simple and sweet, though if you're using multi-window you may need to swap UIApplication.shared.keyWindow! with something more appropriate. Note that we deal with the issue you faced where the element was a UITableTextAccessibilityElement when we handle UIAccessibilityElement since UITableTextAccessibilityElement is a private, internal Apple class.