我发现UIApplication在调用其canPerformAction（...）方法时对内部**_handleLegacyEmojiKeyboardShortcut：**选择器响应true。我不知道为什么会发生这种情况，但它似乎在窗口调整大小（例如旋转设备）后开始响应true。
我通过以下跟踪代码发现了这一点，该代码针对的是keyCommands被覆盖的视图：

func processResponders(_ action: Selector, withSender sender: Any?, next: UIResponder?) {
    if let next {
        let result = next.canPerformAction(action, withSender: sender)
        print("******** canPerformAction \(next) \(action) \(String(describing: sender)) \(result)")
        processResponders(action, withSender: sender, next: next.next)
    }
}

override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
    
    let result = super.canPerformAction(action, withSender: sender)
    print("******** canPerformAction \(action) \(String(describing: sender)) \(result)")
    processResponders(action, withSender: sender, next: next)
    return result
}

我选择的解决方案是定义一个custom UIApplication，并使用以下命令来阻止应用程序类返回true：

import UIKit

class CustomApplication: UIApplication {
    
    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        guard sender is UIKeyCommand == false else { return false }
        return super.canPerformAction(action, withSender: sender)
    }

}