无法指定类型'SlideAnimation.Type'的值来键入'UIViewControllerTransitioningDelegate？

Question

我正在尝试向我的应用添加自定义segue动画，但不断收到此错误：

无法将类型为“SlideAnimation.Type”的值指定为“UIViewControllerTransitioningDe”

我的ViewController代码：

import UIKit

class ViewController: UIViewController{
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let destination = segue.destination
        destination.transitioningDelegate = SlideAnimation
    }
}

我的SlideAnimation.swift代码：

import UIKit

class SlideAnimation: NSObject,UIViewControllerAnimatedTransitioning,UIViewControllerTransitioningDelegate {
    let duration = 0.5

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

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

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

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let toView = transitionContext.view(forKey: UITransitionContextViewKey.to) else{
           return
        }

        let container = transitionContext.containerView
        let screenOffUp = CGAffineTransform(translationX: 0, y: -container.frame.height)
        let screenOffDown = CGAffineTransform(translationX: 0, y:container.frame.height)

        container.addSubview(fromView)
        container.addSubview(toView)

        toView.transform = screenOffUp

        UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 0.8, initialSpringVelocity: 0.8, options: [], animations: {
            fromView.transform = screenOffDown
            fromView.alpha = 0.5
            toView.transform = CGAffineTransform.identity
            toView.alpha = 1


        }) {(success) in
            transitionContext.completeTransition(success)
        }
    }
  }
}

我也是Xcode和这个网站的新手，很抱歉，如果这还不清楚的话。

Answer 1

这个问题是由这条线引起的：

destination.transitioningDelegate = SlideAnimation

您需要传递符合UIViewControllerTransitioningDelegate的类的实例，但是您传递的是类的名称。

您需要创建SlideAnimation的实例并将其设置为委托：

destination.transitioningDelegate = SlideAnimation()

但这实际上会引起一个新问题，因为transitioningDelegate是一个弱参考，并将立即成为nil。您需要创建对SlideAnimation实例的强引用。

import UIKit

class ViewController: UIViewController{
    let transitionDelegate = SlideAnimation()

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let destination = segue.destination
        destination.transitioningDelegate = transitionDelegate
    }
}