UINavigationControllerDelegate 方法，在 ios 8 中使用导航控制器自定义转换

Question

我正在尝试在弹出或推送我的导航控制器时创建一个自定义 t运行sition。我创建了一个符合 UINavigationControllerDelegate 的 t运行sitionManager class。我已经创建了这个 t运行sitionManager 的对象，并将它作为 t运行sitioningDelegate 添加到我的 navigationController。

推送动画运行得很好，但是当我尝试返回上一个时 viewController 我只看到黑屏。

我运行通过许多其他帖子使其工作并尝试了手头的一切，但当我弹出时它仍然没有显示以前的 ViewController。

t运行sitionManager 的代码在这里：

import UIKit

class BRTransitionManager: NSObject, UINavigationControllerDelegate, UIViewControllerAnimatedTransitioning {

    private var presenting = true

    func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {

        if  operation == UINavigationControllerOperation.Push{
            self.presenting = true
        } else if operation == UINavigationControllerOperation.Pop{
            self.presenting = false
        }

        return self
    }

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        let container = transitionContext.containerView()
        let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)!
        let toView = transitionContext.viewForKey(UITransitionContextToViewKey)!

        // set up from 2D transforms that we'll use in the animation
        let offScreenRight = CGAffineTransformMakeTranslation(container.frame.width, 0)
        let offScreenLeft = CGAffineTransformMakeTranslation(-container.frame.width, 0)

        // prepare the toView for the animation
        if (self.presenting == true) {
            // add the both views to our view controller
            container.addSubview(toView)
            // container.addSubview(fromView)

            toView.transform = offScreenRight
        } else {
            toView.transform = offScreenLeft
        }

        let duration = self.transitionDuration(transitionContext)
        UIView.animateWithDuration(duration, delay: 0.0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.8, options: nil, animations: {

            if (self.presenting == true) {
                fromView.transform = offScreenLeft
            } else {
                fromView.transform = offScreenRight
            }

            toView.transform = CGAffineTransformIdentity

        }, completion: { finished in

            transitionContext.completeTransition(true)
        })
    }

    func transitionDuration(transitionContext: UIViewControllerContextTransitioning) -> NSTimeInterval {
        return 0.8
    }   
}

Answer 1

UINavigationController 维护对其委托的弱引用。如果没有强引用，则 UINavigationControllerDelegate 对象在转换完成后被释放。

您可以在故事板编辑器中设置委托对象。通过将对象从调色板拖动到导航控制器场景中的 First Responder 和 Exit 图标之间来添加一个对象。将其 class 设置为您的委托对象的 class 。确保该模块是您当前的应用程序模块。然后 control-drag 从导航控制器图标到对象图标，然后从弹出菜单中选择 "delegate"。

这似乎维护了对委托对象的强引用。然后委托对象将可用于调用展开转换。您不需要自己创建对象或设置委托引用。

我在 Scott James Remnant 的博客 post 中发现了这种技术。

Scott James Remnant - Custom iOS Segues, Transitions, and Animations - The Right Way

UINavigationControllerDelegate 方法，在 ios 8 中使用导航控制器自定义转换

UINavigationControllerDelegate methods, custom transitioning using navigation controller in ios 8

ios

swift

uinavigationcontroller

custom-transition