实现自定义动画以在iPad上显示指定视图的模态视图

class CustomModalViewController: UIViewController {
    override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
        modalPresentationStyle = .custom
        transitioningDelegate = self
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

extension CustomModalViewController: UIViewControllerTransitioningDelegate {
    func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        return CustomPresentationController(presentedViewController: presented, presenting: presenting)
    }
    
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CustomPresentAnimationController()
    }
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CustomDismissAnimationController()
    }
}

class CustomPresentationController: UIPresentationController {
    override var frameOfPresentedViewInContainerView: CGRect {
        let containerViewSize = containerView?.bounds.size ?? .zero
        let presentedViewSize = presentedViewController.preferredContentSize
        let originX = (containerViewSize.width - presentedViewSize.width) / 2
        let originY = (containerViewSize.height - presentedViewSize.height) / 2
        return CGRect(x: originX, y: originY, width: presentedViewSize.width, height: presentedViewSize.height)
    }
}

class CustomPresentAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.3
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let toViewController = transitionContext.viewController(forKey: .to)!
        let containerView = transitionContext.containerView
        toViewController.view.transform = CGAffineTransform(scaleX: 0.01, y: 0.01)
        containerView.addSubview(toViewController.view)
        
        UIView.animate(withDuration: transitionDuration(using: transitionContext), delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0, options: .curveEaseInOut, animations: {
            toViewController.view.transform = .identity
        }, completion: { _ in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        })
    }
}

class CustomDismissAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.3
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let fromViewController = transitionContext.viewController(forKey: .from)!
        let containerView = transitionContext.containerView
        
        UIView.animate(withDuration: transitionDuration(using: transitionContext), delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0, options: .curveEaseInOut, animations: {
            fromViewController.view.transform = CGAffineTransform(scaleX: 0.01, y: 0.01)
        }, completion: { _ in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        })
    }
}

let modalViewController = CustomModalViewController()
present(modalViewController, animated: true, completion: nil)