Add accessibilityLabel property to ButtonState

[acosmicflamingo]

Attempting to address the following discussion: https://github.com/pointfreeco/swiftui-navigation/discussions/164.

Interfacing with models like AlertState can greatly benefit from adding an accessibilityLabel property in the ButtonState model for VoiceOver users.

[stephencelis]

@acosmicflamingo Thanks for taking the time to PR! TextState actually already supports accessibility labels, but I assume that you're looking to expose this info to UIKit? Can you sketch out some code you'd like to work in UIKit and we can consider how to attack it?

[acosmicflamingo]

@stephencelis yeah, it just seems like this information gets lost in UIKit. Although TextState already supports accessibility labels, doing something like this does not the effect you'd think:

extension AlertState where Action == Never {
  @MainActor
  fileprivate static let emailAddressInvalid: Self = {
    let data = AlertState(
      title: TextState(
        WishKitExtensionsStrings.RequestAFeatureViewController
        .Alert.EmailAddressInvalid.title
      ),
      buttons: [
        .default(
          TextState("Hello, world!")
            .accessibilityLabel("LOL")
        )
      ]
    )
    return data
  }()

If I were to do something like let label = SwiftUI.Text("Hello, world").accessibilityLabel("LOL"), I can't just extract it with let accessibilityLabel = label.accessibilityLabel, which of course is never needed because SwiftUI lazily loads them; SwiftUI just "knows" what to do. Plus, accessibilityLabel behavior is treated as a modifier, so I don't even know what would happen if you were to do something like TextState("Hello, world!").accessibilityLabel("LOL1").accessibilityLabel("LOL2")

With respect to TextState supporting accessibility labels, this is exactly where the information is lost:

extension UIAlertAction {
  convenience init<Action>(
    _ button: ButtonState<Action>,
    action handler: @escaping (_ action: Action?) -> Void
  ) {
    self.init(
      title: String(state: button.label),   // where accessibilityLabel does not make its way to UIAlertAction
      style: button.role.map(UIAlertAction.Style.init) ?? .default
    ) { _ in
      button.withAction(handler)
    }
  }
}

[acosmicflamingo]

With that being said, keep in mind that there may be limitations that come from Apple themselves. For example, our own @ZevEisenberg created this years ago, and it doesn't look like it's been addressed: http://www.openradar.me/27286870.

Apple likes to preach a lot about accessibility, but even they have a bunch of blind-spots in their codebase and apps. I had to do this hack to support accessibility labels in my UISegmentedControl instances:

// Based on this answer: 
// https://stackoverflow.com/questions/8833967/how-do-i-set-the-accessibility-label-for-a-particular-segment-of-a-uisegmentedco/59898440#59898440

import Foundation
import UIKit

extension UISegmentedControl {
  public func insertSegmentA11y(action: UIAction, at segment: Int, animated: Bool) {
    insertSegment(action: action, at: segment, animated: animated)
    // Horrible that Apple's UISegmentedControl does not seem to be
    // capable of setting its segments' accessibility labels or
    // its accessibilityUserInputLabels if it's been set in UIAction
    // instance
    if let segmentView = accessibilityElement(at: segment) as? UIView {
      segmentView.accessibilityLabel = action.accessibilityLabel
      segmentView.accessibilityUserInputLabels = action.accessibilityUserInputLabels
    }
  }
}

[stephencelis]

    self.init(
      title: String(state: button.label),   // where accessibilityLabel does not make its way to UIAlertAction
      style: button.role.map(UIAlertAction.Style.init) ?? .default
    ) { _ in
      button.withAction(handler)
    }

How does UIAlertController accessibility work in general? Would you assign the string to UIAlertAction.accessibilityLabel, or does that not work?

[stephencelis]

@acosmicflamingo Just wondering if these changes would be enough to do what you want, or if there's more:

diff --git a/Sources/SwiftUINavigationCore/TextState.swift b/Sources/SwiftUINavigationCore/TextState.swift
index 09ac2ee98..c90619832 100644
--- a/Sources/SwiftUINavigationCore/TextState.swift
+++ b/Sources/SwiftUINavigationCore/TextState.swift
@@ -380,6 +380,15 @@
       return `self`
     }

+    public var accessibilityLabel: TextState? {
+      for modifier in self.modifiers.reversed() {
+        if case let .accessibilityLabel(accessibilityLabel) = modifier {
+          return accessibilityLabel
+        }
+      }
+      return nil
+    }
+
     public func accessibilityTextContentType(_ type: AccessibilityTextContentType) -> Self {
       var `self` = self
       `self`.modifiers.append(.accessibilityTextContentType(type))
diff --git a/Sources/UIKitNavigation/Navigation/UIAlertController.swift b/Sources/UIKitNavigation/Navigation/UIAlertController.swift
index c70a70aec..dd92dec5a 100644
--- a/Sources/UIKitNavigation/Navigation/UIAlertController.swift
+++ b/Sources/UIKitNavigation/Navigation/UIAlertController.swift
@@ -79,6 +79,9 @@
       ) { _ in
         button.withAction(handler)
       }
+      if #available(iOS 15, *) {
+        self.accessibilityLabel = button.label.accessibilityLabel.map { String(state: $0) }
+      }
     }
   }
 #endif

[acosmicflamingo]

@stephencelis that is correct. If you set a UIAlertAction.accessibilityLabel property and then pass it to UIAlertController via addAction, that is enough for it to just work.

As to the diffs you've provided, that looks perfect and exactly what I need. To be completely sure, I will add those changes and run some tests.

[acosmicflamingo]

@stephencelis works like a charm! With that being said, took a bit for me to get it to work because there is duplicate logic here that should be removed in swift-composable-architecture repo: https://github.com/pointfreeco/swift-composable-architecture/blob/35556a66f28b579625ecf50da2d4bc0d6ad3fa4e/Sources/ComposableArchitecture/UIKit/AlertStateUIKit.swift#L219

[stephencelis]

@acosmicflamingo Wanna update this PR and we can get it merged? We should also remove any duplicate logic in the corresponding TCA branch here: https://github.com/pointfreeco/swift-composable-architecture/pull/3180

[acosmicflamingo]

@stephencelis sure! I'm trying to figure out why deleting the duplicate code breaks the logic in AlertStateUIKit. Once I do, I'll update this PR and create another one for swift-composable-architecture. Thanks a bunch for all your help!

[acosmicflamingo]

@stephencelis want me to squash it all in one commit?

[acosmicflamingo]

Thanks for your help Stephen! Couldn't have done it without your suggestions :D