如何在Xcode 12中实现反向的视图控制器水平翻转转场？

以下是几种直接落地的解决方案，适配Xcode 12及iOS 14+环境：

方法一：自定义导航控制器转场代理 #

通过实现导航控制器的代理方法，替换默认的push转场动画，实现左向右的滑入效果：

// 自定义导航控制器
class CustomNavController: UINavigationController, UINavigationControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
    }
    
    func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        // 仅修改push操作的动画
        guard operation == .push else { return nil }
        return ReversePushAnimator()
    }
}

// 自定义反向push动画器
class ReversePushAnimator: NSObject, UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.35 // 和系统默认动画时长保持一致
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let toView = transitionContext.view(forKey: .to) else { return }
        let container = transitionContext.containerView
        
        // 初始状态：目标视图在屏幕左侧外
        toView.frame = CGRect(x: -container.bounds.width, y: 0, width: container.bounds.width, height: container.bounds.height)
        container.addSubview(toView)
        
        // 执行滑入动画
        UIView.animate(withDuration: transitionDuration(using: transitionContext)) {
            toView.frame = container.bounds
        } finished: { success in
            transitionContext.completeTransition(success && !transitionContext.transitionWasCancelled)
        }
    }
}

使用时，将原导航控制器替换为CustomNavController即可。

方法二：手动使用CATransition触发转场 #

如果只是特定场景需要反向转场，无需全局修改，可以直接在跳转前添加自定义过渡动画：

// 在跳转逻辑中添加
let targetVC = YourTargetViewController()
let transition = CATransition()
transition.duration = 0.35
transition.type = .push
transition.subtype = .fromLeft // 指定从左向右进入
navigationController?.view.layer.add(transition, forKey: kCATransition)
// 必须设置animated为false，避免系统默认动画冲突
navigationController?.pushViewController(targetVC, animated: false)

方法三：适配Modal转场（如果是模态跳转） #

若需修改模态视图的转场方向，可通过设置视图控制器的转场代理实现：

// 在发起模态跳转的控制器中
class PresentingVC: UIViewController, UIViewControllerTransitioningDelegate {
    func presentTargetVC() {
        let targetVC = YourTargetViewController()
        targetVC.transitioningDelegate = self
        targetVC.modalPresentationStyle = .fullScreen
        present(targetVC, animated: true)
    }
    
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return ReverseModalAnimator()
    }
}

class ReverseModalAnimator: NSObject, UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.35
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let toView = transitionContext.view(forKey: .to) else { return }
        let container = transitionContext.containerView
        
        toView.frame = CGRect(x: -container.bounds.width, y: 0, width: container.bounds.width, height: container.bounds.height)
        container.addSubview(toView)
        
        UIView.animate(withDuration: transitionDuration(using: transitionContext)) {
            toView.frame = container.bounds
        } finished: { success in
            transitionContext.completeTransition(success)
        }
    }
}

注意事项 #

• 保持动画时长与系统默认一致（0.35秒），避免破坏用户习惯
• 若使用transform反转视图，需注意子视图的镜像问题，不推荐这种方式
• 测试时覆盖横竖屏场景，确保转场逻辑稳定

内容的提问来源于stack exchange，提问作者something