替换后退按钮，但保持滑动以向后导航

Question

首先，我注意到有一个similar question。但是，我想问一下 Swift 中的解决方案。这是我的代码：

override func viewDidLoad() {
    super.viewDidLoad()
    navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Button", style: .Plain, target: self, action: nil)
}

我想替换后退按钮，但保持滑动以供用户向后导航。但是，这会禁用滑动。我无法在上面的链接中获得接受的答案和建议的答案。这是我试图翻译成 Swift 的内容。

let appearanceNavigationBar = UINavigationBar.appearance()
appearanceNavigationBar.backIndicatorImage = UIImage(named: "back")
appearanceNavigationBar.backIndicatorTransitionMaskImage = UIImage(named: "back")
appearanceNavigationBar.tintColor = UIColor.whiteColor()

我正在使用 Xcode 8.0 beta、Swift 2.3 并在 iOS 10.0 中进行测试。任何帮助将不胜感激。

Answer 1

我用过这个，效果很好：

self.navigationController.interactivePopGestureRecognizer.delegate = nil;

Answer 2

接受的答案不完整。如果您配置了故事板转场，并且您在第一个视图控制器上尝试“向后滑动”手势，您可能无法触发转场。

考虑所有边缘情况的最佳解决方案是：

class QFNavigationController:UINavigationController, UIGestureRecognizerDelegate, UINavigationControllerDelegate{
    override func viewDidLoad() {
        super.viewDidLoad()
        interactivePopGestureRecognizer?.delegate = self
        delegate = self
    }

    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        super.pushViewController(viewController, animated: animated)
        interactivePopGestureRecognizer?.isEnabled = false
    }

    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
        interactivePopGestureRecognizer?.isEnabled = true
    }

    // IMPORTANT: without this if you attempt swipe on
    // first view controller you may be unable to push the next one
    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        return viewControllers.count > 1
    }

}

现在只需在需要时使用QFNavigationController。

Answer 3

如this answer 中所述将委托设置为nil 会导致iOS 11 中出现一些讨厌的错误，例如this one

但是一般来说，存根委托的想法是好的。比如可以写如下代码

final class NavigationController: UINavigationController {
    private var customDelegate: InteractivePopGestureRecognizerDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()

        customDelegate = InteractivePopGestureRecognizerDelegate(
            originalDelegate: interactivePopGestureRecognizer?.delegate,
            navigationController: self
        ) 
        interactivePopGestureRecognizer?.delegate = customDelegate
    }
}

然后您可以使用自定义委托来解决问题的根本原因

final class InteractivePopGestureRecognizerDelegate:
    NSObject,
    UIGestureRecognizerDelegate
{
    private weak var originalDelegate: UIGestureRecognizerDelegate?
    private weak var navigationController: UINavigationController?

    init(
        originalDelegate: UIGestureRecognizerDelegate?,
        navigationController: UINavigationController)
    {
        self.originalDelegate = originalDelegate
        self.navigationController = navigationController
    }

    func gestureRecognizer(
        _ gestureRecognizer: UIGestureRecognizer,
        shouldReceive touch: UITouch)
        -> Bool
    {
        if let originalDelegate = originalDelegate,
            let result = originalDelegate.gestureRecognizer?(
                gestureRecognizer,
                shouldReceive: touch)
        {
            if !result {
                // Your interactive pop gesture got cancelled here

                // Perform sanity check of pop possibility
                if (navigationController?.viewControllers.count ?? 0) < 2 {
                    return result
                }

                if navigationController?.navigationBar.isHidden == true {
                    // Return true here if you want to swipe even without navigation bar
                    return result
                }

                // Enable pop gesture
                return true
            }
        } else {
            return true
        }
    }

    ...
    // Proxy all other `UIGestureRecognizerDelegate` methods to the originalDelegate here
    ...
}

当然，这有点棘手，将来可能无法使用（就像其他所有黑客一样）

Answer 4

好的，所以 3 年过去了，您可能不再需要解决此问题的方法了：) 但也许这会帮助其他人解决此问题。这实际上非常简单：您只需要配置后退按钮，它将从第一个视图控制器显示在第二个视图控制器上。这是一个例子：

class FirstViewController: UIViewController {
  override func viewDidLoad() {
    let backButton = UIBarButtonItem(image: UIImage(systemName: "chevron.left.circle.fill"), style: .done, target: nil, action: nil)
    navigationItem.backBarButtonItem = backButton
  }

  func presentSecondViewController() {
    navigationController?.pushViewController(SecondViewController(), animated: true)
  }
}

以这种方式配置 FirstViewController 将允许您在 SecondViewController 上显示自定义后退按钮并保持向后滑动手势。