ios - UITabBarController canBecomeFirstResponder 方法未被调用

Question

看完http://nshipster.com/uikeycommand/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 Controller 的方法。这样您应该能够获得按键。