ios - 如何使用 5 个以上的 ViewController 为 UITabBarController 中的过渡设置动画？

Question

我有一个 UITabBarController，它有 9 个 View Controller ，我使用前进和后退按钮自定义处理导航。我创建了一个 UIViewControllerAnimatedTransitioning 对象来处理动画(简单的从左到右)，它在委托(delegate)方法中返回:

tabBarController(_ tabBarController: UITabBarController, animationControllerForTransitionFrom fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning?

但是，在选择第五个索引时和之后，不再调用此函数(因为它现在由 UIMoreNavigationController 处理。是否有动画委托(delegate)或我应该以某种方式处理它UIMoreNavigationController 实例？

Answer 1

您需要指定 moreNavigationController 的委托(delegate)。所以在你的 UITabBarController 类中你需要:

        self.moreNavigationController.delegate = strongDelegate // where strongDelegate is a local instance of MyControllerDelegate as defined below

然后委托(delegate)应该实现 navigationController 函数，该函数将调用适用的 UIViewControllerAnimatedTransitioning 实例:

class MyControllerDelegate: NSObject, UINavigationControllerDelegate {

func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    switch operation {
    case .push:
        return MyPresentationAnimationController(isPresenting: true)
    case .pop:
        return MyPresentationAnimationController(isPresenting: false)
    default:
        return nil
    }
}

您的 animateTransition 函数包含神奇发生的逻辑:

class MyPresentationAnimationController : NSObject, UIViewControllerAnimatedTransitioning {

private let isPresenting: Bool

init(isPresenting: Bool) {
    self.isPresenting = isPresenting
}

func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
    return TimeInterval(UINavigationController.hideShowBarDuration)
}

func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
    guard
        let toView = transitionContext.view(forKey: .to),
        let fromView = transitionContext.view(forKey: .from)
        else {
            return
    }
    let containerView = transitionContext.containerView

    // TODO: Implement the logic with UIView.animateKeyframes here ...

}