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[已解决]swift中页面切换时找不到UITransitionContextFromViewKey

iOS crifan 800浏览 0评论

折腾:

[未解决]swift中让视图ViewController从左向右滑入显示+从右向左消失

期间,用代码:

        let filterVC = SingletonFilterCustomerVC()

//        filterVC.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext

        filterVC.modalPresentationStyle = UIModalPresentationStyle.Custom

        let transitionManager = TransitionManager2()

        filterVC.transitioningDelegate = transitionManager

        self.presentViewController(filterVC, animated: true, completion: nil)

import UIKit

class TransitionManager2: NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate {

    private var presenting = true

    // MARK: UIViewControllerAnimatedTransitioning protocol methods

    // animate a change from one viewcontroller to another

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {

        // get reference to our fromView, toView and the container view that we should perform the transition in

        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

        toView.transform = self.presenting ? offScreenRight : offScreenLeft

        // set the anchor point so that rotations happen from the top-left corner

        toView.layer.anchorPoint = CGPoint(x:0, y:0)

        fromView.layer.anchorPoint = CGPoint(x:0, y:0)

        // updating the anchor point also moves the position to we have to move the center position to the top-left to compensate

        toView.layer.position = CGPoint(x:0, y:0)

        fromView.layer.position = CGPoint(x:0, y:0)

        // add the both views to our view controller

        container!.addSubview(toView)

        container!.addSubview(fromView)

        // get the duration of the animation

        // DON’T just type ‘0.5s’ — the reason why won’t make sense until the next post

        // but for now it’s important to just follow this approach

        let duration = self.transitionDuration(transitionContext)

        // perform the animation!

        // for this example, just slid both fromView and toView to the left at the same time

        // meaning fromView is pushed off the screen and toView slides into view

        // we also use the block animation usingSpringWithDamping for a little bounce

        UIView.animateWithDuration(duration, delay: 0.0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: [], animations: {

            // slide fromView off either the left or right edge of the screen

            // depending if we’re presenting or dismissing this view

            fromView.transform = self.presenting ? offScreenLeft : offScreenRight

            toView.transform = CGAffineTransformIdentity

            }, completion: { finished in

                // tell our transitionContext object that we’ve finished animating

transitionContext.completeTransition(true)

        })

    }

但是:

        let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)!

出错:

搜:

uitransitioncontextfromviewkey nil

uiview – Nil when unwrapping viewForKey(UITransitionContextFromViewKey) (Swift) – Stack Overflow

说是:把modalPresentationStyle的custom设置,去掉,即可规避此bug

-》但是我此处是:

必须设置为cusom,否则顶部内容不能覆盖掉导航栏的内容

rdar://17961976: transitionContext viewForKey: always returns nil for presenting view during modal transition

UIViewControllerContextTransitioning Protocol Reference

iOS8 View Controller transitioning bug | Splinter Software

把Custom改为FullScreen试试:

//        filterVC.modalPresentationStyle = UIModalPresentationStyle.Custom

        filterVC.modalPresentationStyle = UIModalPresentationStyle.FullScreen

好像是可以的:

至少是

let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)!

可以正常获得值了。

但是转换后的效果是:

整个屏幕都转换过来了

而不是,在原有内容的基础上去覆盖的显示

-》所以还是要去改为:

去换成:

//        filterVC.modalPresentationStyle = UIModalPresentationStyle.Custom

//        filterVC.modalPresentationStyle = UIModalPresentationStyle.FullScreen

        filterVC.modalPresentationStyle = UIModalPresentationStyle.OverFullScreen

试试

结果也会导致:

        let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)!

挂掉

-》UITransitionContextFromViewKey找不到。

所以,还是算了:

还是换回:

filterVC.modalPresentationStyle = UIModalPresentationStyle.Custom

然后通过:

animationControllerForPresentedController时记录的sourceController去保存,用于后续animateTransition的使用

ios – “From View Controller” disappears using UIViewControllerContextTransitioning – Stack Overflow

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