基于父视图 ID 的 UI 子视图的可访问性标识符

Question

我有一个自定义视图，其中包含一些子视图，例如标签和文本字段。当我在一个控制器中使用多个自定义视图时，我想知道子视图可访问性标识符。我想要实现的是设置父标识符（parent_accessibility_identifier），而子视图标识符可以是它的扩展（例如parent_accessibility_identifier_label，parent_accessibility_identifier_text_field） .我们可以通过将父标识符可访问地设置为 false 并将标签和文本添加到子视图中来做到这一点，但是有没有更好的方法来做到这一点？此代码在子视图类中不起作用。

public override var accessibilityIdentifier: String? {
    didSet {
        if let accessibilityIdentifier = self.accessibilityIdentifier {
            self.accessibilityIdentifier = accessibilityIdentifier + "_label"
        }
    }
}

自定义视图类中的这项工作

public override var accessibilityIdentifier: String? {
    didSet {
        guard let accessibilityIdentifier = accessibilityIdentifier else { return }
        
        textLabel.accessibilityIdentifier = accessibilityIdentifier + "_text_label"
    }
}

Answer 1

我建议为此使用 swizzling。它使您能够覆盖系统级框架的打开属性和函数的行为。

1. 首先，将 swizzling 代码放在某处：

    ///
    extension UIView {
   
        /**
         */
        class func swizzle() {
            let orginalSelectors = [
                #selector(getter: accessibilityIdentifier),
            ]
            let swizzledSelectors = [
                #selector(getter: swizzledAccessibilityIdentifier)
            ]
   
            let orginalMethods = orginalSelectors.map { class_getInstanceMethod(UIView.self, $0) }
            let swizzledMethods = swizzledSelectors.map { class_getInstanceMethod(UIView.self, $0) }
   
            orginalSelectors.enumerated().forEach { item in
                let didAddMethod = class_addMethod(
                    UIView.self,
                    item.element,
                    method_getImplementation(swizzledMethods[item.offset]!),
                    method_getTypeEncoding(swizzledMethods[item.offset]!))
   
                if didAddMethod {
                    class_replaceMethod(
                        UIView.self,
                        swizzledSelectors[item.offset],
                        method_getImplementation(orginalMethods[item.offset]!),
                        method_getTypeEncoding(orginalMethods[item.offset]!))
                } else {
                    method_exchangeImplementations(orginalMethods[item.offset]!, swizzledMethods[item.offset]!)
                }
            }
        }
   
        /// that's where you override `accessibilityIdentifier` getter for 
        @objc var swizzledAccessibilityIdentifier: String {
            if let parentIdentifier = superview?.accessibilityIdentifier {
                return "\(parentIdentifier)_\(self.swizzledAccessibilityIdentifier)"
            } else {
                return self.swizzledAccessibilityIdentifier
            }
        }
    }
   

2. 致电UIView.swizzle()。通常，您在应用程序启动时执行此操作。在AppDelegate 或类似的地方。

3. 设置视图层次结构、分配标识符和测试：

    class ParentView: UIView {}
    class SubclassedChildView: UIView {}
   
    let parentView = ParentView()
    let child1 = SubclassedChildView()
    let child2 = UIView()
   
    parentView.accessibilityIdentifier = "parent"
    child1.accessibilityIdentifier = "child1"
    child2.accessibilityIdentifier = "child2"
   
    parentView.addSubview(child1)
    child1.addSubview(child2)
   
    print(parentView.accessibilityIdentifier) // "parent"
    print(child1.accessibilityIdentifier) // "parent_child1"
    print(child2.accessibilityIdentifier) // "parent_child1_child2"