ios swift 页面跳转动画 水平进入或退出（左到右 右到左跳转）

本介绍UIViewController之间跳转时，通过配置页面动画过渡，把页面跳转动画弄成左到右或者右到左的方法。

代码摘抄自： How to present view controller from right to left in iOS using Swift

创建页面过渡动画类：

class RightToLeftTransition: NSObject, UIViewControllerAnimatedTransitioning {
    let duration: TimeInterval = 0.25

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

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let container = transitionContext.containerView
        let toView = transitionContext.view(forKey: .to)!

        container.addSubview(toView)
        toView.frame.origin = CGPoint(x: toView.frame.width, y: 0)

        UIView.animate(withDuration: duration, delay: 0, options: .curveEaseOut, animations: {
            toView.frame.origin = CGPoint(x: 0, y: 0)
        }, completion: { _ in
            transitionContext.completeTransition(true)
        })
    }
}

class LeftToRightTransition: NSObject, UIViewControllerAnimatedTransitioning {
    let duration: TimeInterval = 0.25

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

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let container = transitionContext.containerView
        let fromView = transitionContext.view(forKey: .from)!

        container.addSubview(fromView)
        fromView.frame.origin = .zero

        UIView.animate(withDuration: duration, delay: 0, options: .curveEaseIn, animations: {
            fromView.frame.origin = CGPoint(x: fromView.frame.width, y: 0)
        }, completion: { _ in
            fromView.removeFromSuperview()
            transitionContext.completeTransition(true)
        })
    }
}

在页面跳转前的上个页面 配置下个页面的过渡动画

class ViewController: UIViewController {
    var presentTransition: UIViewControllerAnimatedTransitioning?
    var dismissTransition: UIViewControllerAnimatedTransitioning?

    func jumpToVc(animated: Bool) {
        let vc = UIViewController() // 这个是要跳到的viewController

        presentTransition = RightToLeftTransition()
        dismissTransition = LeftToRightTransition()

        vc.modalPresentationStyle = .custom
        vc.transitioningDelegate = self

        present(vc, animated: true, completion: { [weak self] in
            self?.presentTransition = nil
        })
    }
}

实现过渡协议，返回配置的动画过渡。

extension ViewController: UIViewControllerTransitioningDelegate {
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return presentTransition
    }

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