在 SwiftUI 和 UIKit 中创建易于访问的 App

1:54 - Add the accessibility toggle trait

import SwiftUI

struct FilterButton: View {
    @State var filter: Bool = false

    var body: some View {
        Button(action: { filter.toggle() }) {
            Text("Filter")
        }
        .background(filter ? darkGreen : lightGreen)
        .accessibilityAddTraits(.isToggle)
    }
}

2:31 - Add the accessibility toggle trait with UIKit

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let filterButton = UIButton(type: .custom)

        setupButtonView()

        filterButton.accessibilityTraits = [.toggleButton]

        view.addSubview(filterButton)
    }
}

3:43 - Post an accessibility notification

import SwiftUI

struct ContentView: View {
    var body: some View {
        NavigationView {
            PhotoFilterView
                .toolbar {
                    Button(action: {
                        AccessibilityNotification.Announcement("Loading Photos View")
                            .post()
                    }) {
                        Text("Photos")
                    }
                }
        }
    }
}

5:13 - Assign announcement priority

import SwiftUI

struct ZoomingImageView: View {
  
    var defaultPriorityAnnouncement = AttributedString("Opening Camera")

    var lowPriorityAnnouncement: AttributedString {
        var lowPriorityString = AttributedString("Camera Loading")
        lowPriorityString.accessibilitySpeechAnnouncementPriority = .low
        return lowPriorityString
    }
    
    var highPriorityAnnouncement: AttributedString {
        var highPriorityString = AttributedString("Camera Active")
        highPriorityString.accessibilitySpeechAnnouncementPriority = .high
        return highPriorityString
    }
  
    // ...
}

5:46 - Post announcements with priority set

import SwiftUI

struct CameraButton: View {
    
    // ...
  
    var body: some View {
        Button(action: {
            // Open Camera Code
            AccessibilityNotification.Announcement(defaultPriorityAnnouncement).post()
            // Camera Loading Code
            AccessibilityNotification.Announcement(lowPriorityAnnouncement).post()
            // Camera Loaded Code
            AccessibilityNotification.Announcement(highPriorityAnnouncement).post()
        }) {
            Image("Camera")
           }
        }
    }
}

6:15 - Assign announcement priority with UIKit

class ViewController: UIViewController {
    let defaultAnnouncement = NSAttributedString(string: "Opening Camera", attributes: 
        [NSAttributedString.Key.UIAccessibilitySpeechAttributeAnnouncementPriority: 
        UIAccessibilityPriority.default]
    )

    let lowPriorityAnnouncement = NSAttributedString(string: "Camera Loading", attributes:   
        [NSAttributedString.Key.UIAccessibilitySpeechAttributeAnnouncementPriority:
        UIAccessibilityPriority.low]
    )

    let highPriorityAnnouncement = NSAttributedString(string: "Camera Active", attributes: 
        [NSAttributedString.Key.UIAccessibilitySpeechAttributeAnnouncementPriority:  
        UIAccessibilityPriority.high]
    )

    // ...
}

6:56 - Add the accessibility zoom action

struct ZoomingImageView: View {
    @State private var zoomValue = 1.0
    @State var imageName: String?

    var body: some View {
        Image(imageName ?? "")
            .scaleEffect(zoomValue)
            .accessibilityZoomAction { action in
                let zoomQuantity = "\(Int(zoomValue)) x zoom"
                switch action.direction {
                case .zoomIn:
                    zoomValue += 1.0
                    AccessibilityNotification.Announcement(zoomQuantity).post()
                case .zoomOut:
                    zoomValue -= 1.0
                    AccessibilityNotification.Announcement(zoomQuantity).post()
                }
            }
    }
}

7:18 - Add the accessibility zoom action with UIKit

import UIKit

class ViewController: UIViewController {
    let zoomView = ZoomingImageView(frame: .zero)
    let imageView = UIImageView(image: UIImage(named: "tree"))

    override func viewDidLoad() {
        super.viewDidLoad()
        zoomView.isAccessibilityElement = true
        zoomView.accessibilityLabel = "Zooming Image View"
        zoomView.accessibilityTraits = [.image, .supportsZoom]

        zoomView.addSubview(imageView)
        view.addSubview(zoomView)
    }
}

7:43 - Respond to accessibility zoom actions with UIKit

import UIKit 

class ZoomingImageView: UIScrollView {
    override func accessibilityZoomIn(at point: CGPoint) -> Bool {
        zoomScale += 1.0

        let zoomQuantity = "\(Int(zoomValue)) x zoom"  
        UIAccessibility.post(notification: .announcement, argument: zoomQuantity)
        return true
    }

    override func accessibilityZoomOut(at point: CGPoint) -> Bool {
        zoomScale -= 1.0

        let zoomQuantity = "\(Int(zoomValue)) x zoom" 
        UIAccessibility.post(notification: .announcement, argument: zoomQuantity)             
        return true
    }
}

10:10 - Use accessibility direct touch options

import SwiftUI

struct KeyboardKeyView: View {
    var soundFile: String
    var body: some View {
        Rectangle()
            .fill(.white)
            .frame(width: 35, height: 80)
            .onTapGesture(count: 1) {
                playSound(sound: soundFile, type: "mp3")
            }            
            .accessibilityDirectTouch(options: .silentOnTouch)
    }
}

10:46 - Use accessibility direct touch options with UIKit

import UIKit

class ViewController: UIViewController {
    let waveformButton = UIButton(type: .custom)

    override func viewDidLoad() {
        super.viewDidLoad()
        
        waveformButton.accessibilityTraits = .allowsDirectInteraction
        waveformButton.accessibilityDirectTouchOptions = .silentOnTouch
        waveformButton.addTarget(self, action: #selector(playTone), for: .touchUpInside)
        
        view.addSubview(waveformButton)
    }
}

12:21 - Set the accessibility content shape

import SwiftUI

struct ImageView: View {
    var body: some View {
        Image("circle-red")
            .resizable()
            .frame(width: 200, height: 200)
            .accessibilityLabel("Red")
            .contentShape(.accessibility, Circle())
    }
}

13:35 - Update accessibility values using block-based setters with UIKit

import UIKit 

class ViewController: UIViewController {
    var isFiltered = false

    override func viewDidLoad() {
        super.viewDidLoad()
        // Set up views
        zoomView.accessibilityValueBlock = { [weak self] in
            guard let self else { return nil }
            return isFiltered ? "Filtered" : "Not Filtered"
        }
    }
}