Swift

Question

我正在使用自定义导航控制器来显示和隐藏两个 ViewController。将调用 ViewController 以显示一些电影细节的代码是：

func tapGestureRecognizer(gestureRecognizer: UITapGestureRecognizer){
        self.searchBarTop.endEditing(true)
        let p = gestureRecognizer.locationInView(self.collectionViewMovies)
        let tag = gestureRecognizer.view?.tag
        if tag == 1{
            if let indexPath : NSIndexPath = (self.collectionViewMovies?.indexPathForItemAtPoint(p)){
                if let cell = self.collectionViewMovies.cellForItemAtIndexPath(indexPath){
                    cellAnimation.imageBlurCell(cell, style: .Light, alpha: 1.0, completion: { (complete) -> Void in
                        if let record = self.fetchedResultsController.objectAtIndexPath(indexPath) as? Movies{
                            let movieId = record.movieid as! Int
                            NSNotificationCenter.defaultCenter().postNotificationName("moviesShouldGetDetails", object: nil, userInfo: ["movieId":movieId])
                            let destination = self.myStoryboard.instantiateViewControllerWithIdentifier("MovieDetails") as! MovieDetailsViewController
                            destination.movieId = movieId
                            self.navigationController?.pushViewController(destination, animated: true)
                        }
                    })
                }
            }
        }
    }

我每次都在创建 MovieDetailsViewController 的新实例。问题是我认为在 NavigationController Pop 之后 ViewController 实例会被杀死，但这并没有发生。我在 MovieDetailsViewController 中有一些观察者，我可以看到该实例仍然运行。 NavigationController 委托是：

func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        if operation == .Push {
            customInteractionController.attachToViewController(toVC)
        }
        customNavigationAnimationController.reverse = operation == .Pop
        return customNavigationAnimationController
    }

    func navigationController(navigationController: UINavigationController, interactionControllerForAnimationController animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return customInteractionController.transitionInProgress ? customInteractionController : nil
    }

控制动画的代码如下，当动画完成时，我试图再次强制弹出导航，但到目前为止没有运气。

import UIKit

class CustomNavigationAnimationController: NSObject, UIViewControllerAnimatedTransitioning {

    var reverse = false

    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return 0.5
    }

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        let containerView = transitionContext.containerView()
        let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
        let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
        let toView = toViewController.view
        let fromView = fromViewController.view
        let direction: CGFloat = reverse ? -1 : 1
        let const: CGFloat = -0.005

        toView.layer.anchorPoint = CGPointMake(direction == 1 ? 0 : 1, 0.5)
        fromView.layer.anchorPoint = CGPointMake(direction == 1 ? 1 : 0, 0.5)

        var viewFromTransform: CATransform3D = CATransform3DMakeRotation(direction * CGFloat(M_PI_2), 0.0, 1.0, 0.0)
        var viewToTransform: CATransform3D = CATransform3DMakeRotation(-direction * CGFloat(M_PI_2), 0.0, 1.0, 0.0)
        viewFromTransform.m34 = const
        viewToTransform.m34 = const

        containerView!.transform = CGAffineTransformMakeTranslation(direction * containerView!.frame.size.width / 2.0, 0)
        toView.layer.transform = viewToTransform
        containerView!.addSubview(toView)

        UIView.animateWithDuration(transitionDuration(transitionContext), animations: {
            containerView!.transform = CGAffineTransformMakeTranslation(-direction * containerView!.frame.size.width / 2.0, 0)
            fromView.layer.transform = viewFromTransform
            toView.layer.transform = CATransform3DIdentity
            }, completion: {
                finished in
                containerView!.transform = CGAffineTransformIdentity
                fromView.layer.transform = CATransform3DIdentity
                toView.layer.transform = CATransform3DIdentity
                fromView.layer.anchorPoint = CGPointMake(0.5, 0.5)
                toView.layer.anchorPoint = CGPointMake(0.5, 0.5)

                if (transitionContext.transitionWasCancelled()) {
                    toView.removeFromSuperview()
                } else {
                    fromView.removeFromSuperview()
                    if self.reverse{
                        print("removing from superview")
                        fromViewController.navigationController?.popViewControllerAnimated(false)
                    }
                }
                transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
        })
    }
}

我在这里错过了什么？我怎样才能杀死我的 MovieDetailsViewController 实例？ NavigationController .Pop 不应该杀死我的实例吗？提前致谢。

Answer 1

你说

I have some Observers inside the MovieDetailsViewController and i can see that the instance still running.

这是否可能意味着您在弹出后保留对 MovieDetailsViewController 的引用？ Swift 的垃圾收集器不会释放视图控制器，直到它不再有任何引用。如果您维护对视图控制器的引用，即使在屏幕外它也会保持活动状态。

Answer 2

在花了一些时间了解 ARC 的工作原理后，我解决了这个问题。我有一些强引用循环，因为一些委托没有像 "weak" 这样声明。另一个问题是在这一行

customInteractionController.attachToViewController(toVC)

此代码将在另一个 class 中使用 NavigationViewController 创建强引用，我只是将此引用更改为弱引用。现在一切正常。

Swift - 导航控制器没有杀死视图控制器实例

Swift - Navigation Controller no Killing View Controller Instance

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