交互式转换:Segue声明

Question

理论问题：在下面的代码中，为什么在"performSegue…."一行，segue没有完全执行？我的意思是，它怎么知道这是一个互动的过渡，为什么"performSegue…"方法的效果与她在其他地方被宣布的效果不同？

FirstViewController.swift

let transitionManager = TransitionManager()

override func viewDidLoad() {
    super.viewDidLoad()
    transitionManager.sourceViewController = self
    // Do any additional setup after loading the view.
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
    let dest = segue.destinationViewController as UIViewController
    dest.transitioningDelegate = transitionManager
    transitionManager.destViewController = dest
}

情节提要

分段是从FirstViewController到SecondViewController。

• 标识符："segueIdentifier"

• Segue：Modal

• 目的地：当前

TransitionManager.swift

class TransitionManager: UIPercentDrivenInteractiveTransition,UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate,UIViewControllerInteractiveTransitioning {
    var interactive = false
    var presenting = false
    var panGesture : UIPanGestureRecognizer!
    var sourceViewController : UIViewController! {
        didSet {
            panGesture = UIPanGestureRecognizer(target: self, action: "gestureHandler:")
            sourceViewController.view.addGestureRecognizer(panGesture)
        }
    }

    func gestureHandler(pan : UIPanGestureRecognizer) {
        let translation = pan.translationInView(pan.view!)
        let d =  translation.x / pan.view!.bounds.width * 0.5        
        switch pan.state {
        case UIGestureRecognizerState.Began :
            interactive = true
            sourceViewController.performSegueWithIdentifier("segueIdentifier", sender: self)

        case UIGestureRecognizerState.Changed :
            self.updateInteractiveTransition(d)
        default :
            interactive = false
            if d > 0.2 || velocity.x > 0 {
                self.finishInteractiveTransition()
            }
            else {
                self.cancelInteractiveTransition()
            }
        }
    }
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        //Something....

        UIView.animateWithDuration(1.0, animations: {
            //Something....
            }, completion: {}
        })
    }
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning) -> NSTimeInterval {
        return 1
    }
    // MARK: UIViewControllerTransitioningDelegate protocol methods
    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        self.presenting = true
        return self
    }
    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        self.presenting = false
        return self
    }
    func interactionControllerForPresentation(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return self.interactive ? self : nil
    }
    func interactionControllerForDismissal(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return self.interactive ? self : nil
    }


}

事实上，我有很多类似的代码，这一个正在工作，但其他非常相似的代码正是我所解释的：segue只是在没有交互转换的情况下执行的。有人能给我解释一下吗？

感谢您的帮助

Answer 1

如果问题是交互式转换动画不是交互式的，我建议在interactionControllerForPresentation:中设置断点

• 确保interactionControllerForPresentation的正确实例按照您认为的方式调用。

  例如，确保destination的viewDidLoad没有替换您在源控制器的prepareForSegue中精心设置的transitioningDelegate。。。如果从A到B，再从B到C进行交互式转换，那么这很容易做到，你在预期B到C时设置的内容可能会干扰你从A到C的意图。

• 确保interactionControllerForPresentation返回您认为应该返回的值（即，确保interactive肯定是true）。

每次我看到手势没有以交互方式启动转换的行为，就像我认为应该的那样，都是因为当在目标控制器的transitioningDelegate中调用interactionControllerForPresentation时，它没有像我预期的那样返回有效的UIViewControllerInteractiveTransitioning（如UIPercentDrivenInteractiveTransition）。

无论如何，您可以通过在interactionControllerForPresentation中添加一条日志语句来诊断这一问题，并且您会看到（a）由于某种原因没有调用它；或者（b）CCD_ 14不是CCD_。