iOS 更改辅助功能焦点

Swift
import UIKit
class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let button = UIButton(type: .system)
        button.setTitle("Focus Button", for: .normal)
        button.sizeToFit()
        button.center = view.center
        view.addSubview(button)
        
        button.isAccessibilityElement = true
        button.accessibilityIdentifier = "focusButton"
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        if let button = view.viewWithTag(1) {
            UIAccessibility.post(notification: .layoutChanged, argument: button)
            UIAccessibility.setFocusToElement(button)
            
            DispatchQueue.mAIn.asyncAfter(deadline: .now() + 2) {
                UIAccessibility.accessibilityElementDidLoseFocus(button)
            }
        }
    }
}