UITabBarController canBecomeFirstResponder 方法未被调用

Question

阅读 http://nshipster.com/uikeycommand/ 后，我想在我的应用程序中使用箭头键在选项卡之间添加导航。但是我无法在 UITabBarController 中接收到按键。下面的相同代码块在 UIViewController 中工作，但在 UITabBarController 中工作。

当我尝试调试时，甚至没有调用 UITabBarController 的 canBecomeFirstResponder 覆盖。我没有在 apple 的文档中找到有用的东西。感谢任何使问题清晰的信息。

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)

    let firstResponderResult = self.becomeFirstResponder()
    println("became first responder \(firstResponderResult)")
}

override func canBecomeFirstResponder() -> Bool {
    return true
}

override var keyCommands: [AnyObject]? {
    return [
        UIKeyCommand(input: UIKeyInputRightArrow, modifierFlags: UIKeyModifierFlags.allZeros, action: "rightArrowClicked:"),
        UIKeyCommand(input: UIKeyInputLeftArrow, modifierFlags: UIKeyModifierFlags.allZeros, action: "leftArrowClicked:")
    ]
}

func rightArrowClicked(sender: UIKeyCommand) {

    let currentIndex = selectedIndex;

    if (currentIndex < viewControllers!.count - 1) {
        selectedIndex = currentIndex + 1;
    }
}

func leftArrowClicked(sender: UIKeyCommand) {
    let currentIndex = selectedIndex;

    if (currentIndex > 0) {
        selectedIndex = currentIndex - 1;
    }
}

Answer 1

我认为您应该覆盖 UITabBarController 中 VC 的 canBecomeFirstResponder 方法，而不是选项卡栏控制器的方法。这样你应该能够得到按键。

Answer 2

iOS13 和 Mac Swift5 中的催化剂：

extension UITabBarController {

    open override var keyCommands: [UIKeyCommand]? {
        return [
            UIKeyCommand(input: UIKeyCommand.inputRightArrow, modifierFlags: .alternate, action: #selector(rightArrowClicked)),
            UIKeyCommand(input: UIKeyCommand.inputLeftArrow, modifierFlags: .alternate, action: #selector(leftArrowClicked))
        ]
    }

    @objc private func rightArrowClicked(sender: UIKeyCommand) {

        let currentIndex = selectedIndex;

        if (currentIndex < viewControllers!.count - 1) {
            selectedIndex = currentIndex + 1;
        }
    }

    @objc private func leftArrowClicked(sender: UIKeyCommand) {
        let currentIndex = selectedIndex;

        if (currentIndex > 0) {
            selectedIndex = currentIndex - 1;
        }
    }

    open override var canBecomeFirstResponder: Bool {
        return true
    }

UITabBarController canBecomeFirstResponder 方法未被调用

UITabBarController canBecomeFirstResponder method not get called

ios

swift

uitabbarcontroller

uiresponder

becomefirstresponder