NSAccessibilityRadioButton implementation in Swift 4

Question

I'm trying to make an NSAccessibilityRadioButton element, but I'm getting ... let's say an unexpected error. Here is what I'm doing

1. I have a base class of NSAccessibilityElement:

   class AccessibilityElementPrototype: NSAccessibilityElement {
     .
     .
     .
   }
   

2. I have another class, which should implement NSAccessibilityRadioButton protocol like this:

   class AccessibilityElementTab: AccessibilityElementPrototype, NSAccessibilityRadioButton {
       func accessibilityValue() -> NSNumber? {
           ...
       }
   }
   

The problem is that I'm getting the following error:

Method 'accessibilityValue()' with Objective-C selector 'accessibilityValue' conflicts with method 'accessibilityValue()' from superclass 'NSAccessibilityElement' with the same Objective-C selector

If someone has already encountered such a problem and has solution, please share.

Answer 1

I'm really happy you asked this, because I thought I was crazy.

It appears, unbelievably, that some of the NSAccessiblity protocols are broken in Swift. I've opened a bug with Apple, and I encourage you do the same. In the mean time, it's fairly easy to work around this, just inconvenient.

You can directly use NSView methods to achieve the same result:

view.setAccessibilityRole(...)
view.setAccessibilityElement(true)

@objc override func accessibilityValue() -> Any? {
    ...
}

Don't forget about setting the accessibiltyElement property to true. I didn't realize that was necessary at first, and couldn't figure out why nothing was showing up. Accessibility Inspector's Show Ignored Elements helped me there.