我正在以模态方式呈现一个具有模糊背景效果的 View Controller 。 iOS 10/XCode 8 引入了我的动画问题。这是演示代码:

let modalVC = ModalViewController(nibName: "ModalViewController", bundle: nil)
modalVC.modalTransitionStyle = .CrossDissolve
modalVC.modalPresentationStyle = .OverFullScreen
presentViewController(modalVC, animated: true, completion: nil)

在 ModalViewController 的 viewDidLoad() 函数上添加模糊:

let blurEffect = UIBlurEffect(style: .Light)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

view.addSubview(blurEffectView)
view.sendSubviewToBack(blurEffectView)

ModalViewController 有一个清晰的背景，我添加了一个带有深色模糊效果的 BlurEffectView。以编程方式尝试使用前面的代码片段和在 Interface Builder 中。

在 iOS 8 和 9 上，.CrossDissolve 过渡负责“淡入淡出”，但在 iOS 10(设备和模拟器)上测试后， View 显示为黑色半透明背景颜色而不是模糊。

.CrossDissolve 动画完成后，背景颜色变为实际模糊效果背景。知道为什么会这样吗？

还尝试在模态视图 Controller 的 viewDidLoad() 的开头和结尾添加 layoutIfNeeded()，但没有成功。我正在使用 swift 2.3

最佳答案

你好，

您需要创建一个新的 UIViewControllerAnimatedTransitioning。

然后在 animateTransition(using transitionContext: UIViewControllerContextTransitioning) 中，您需要编写动画代码。

现在在 iOS 10 中，您可以使用 UIViewPropertyAnimator 为 UIVisualBlurEffect 的 BlurRadius 设置动画。

结果:

这里有一个用法示例:https://github.com/PierrePerrin/PPBlurModalPresentation

首先

你需要创建你的模糊过渡

    class BlurModalPresentation: NSObject,UIViewControllerAnimatedTransitioning {


        func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval{

            return 0.5
        }

//This is the blur view used for transition
        var blurView = UIVisualEffectView(effect: UIBlurEffect(style: UIBlurEffectStyle.light))
        var destinationView : UIView!
        var animator: UIViewPropertyAnimator?

        // This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.
        func animateTransition(using transitionContext: UIViewControllerContextTransitioning){

            let containerView = transitionContext.containerView

            _ = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
            let toVc = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)

            destinationView = toVc!.view
            destinationView.alpha = 0.0

//Here we add the blur view and set it effect to nil
            blurView.effect = nil
            blurView.frame = containerView.bounds

            self.blurTransition(transitionContext) { 

                self.unBlur(transitionContext, completion: { 

                    self.blurView.removeFromSuperview()
                    transitionContext.completeTransition(true)
                })
            }

            containerView.addSubview(toVc!.view)
            containerView.addSubview(blurView)
        }

        //This methods add the blur to our view and our destinationView
        func blurTransition(_ context : UIViewControllerContextTransitioning,completion: @escaping () -> Void){

            UIViewPropertyAnimator.runningPropertyAnimator(withDuration: self.transitionDuration(using: context)/2, delay: 0, options: UIViewAnimationOptions.curveLinear, animations: {

                self.destinationView.alpha = 0.5
                  self.blurView.effect = UIBlurEffect(style: UIBlurEffectStyle.light)
            }, completion: { (position) in
                completion()
            })

        }
        //This Method remove the blur view with an animation
        func unBlur(_ context : UIViewControllerContextTransitioning,completion: @escaping () -> Void){

            UIViewPropertyAnimator.runningPropertyAnimator(withDuration: self.transitionDuration(using: context) / 2, delay:0, options: UIViewAnimationOptions.curveLinear, animations: {

                self.destinationView.alpha = 1.0
                self.blurView.effect = nil
            }, completion: { (position) in
                completion()
            })
        }

    }

然后

您需要在您的ViewController 中设置转换委托(delegate):

import UIKit

class ViewController: UIViewController,UIViewControllerTransitioningDelegate {

    let blurModalPresentation = BlurModalPresentation()

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    func showVC(){

        let str = self.storyboard!
        let vc = str.instantiateViewController(withIdentifier: "YourViewControllerIdentifier")
        vc.transitioningDelegate = self
        self.present(vc, animated: true, completion: nil)
    }


    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
    }

    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?{

        return blurModalPresentation
    }


    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?{

        return blurModalPresentation
    }

}

关于ios - 呈现具有模糊效果的 View Controller ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39644775/