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如何通过缩放呈现UIViewController？

缩放呈现UIViewController是指在iOS应用中，通过缩放动画来展示一个新的UIViewController。这种效果可以使界面更加生动有趣，提高用户体验。以下是如何实现缩放呈现UIViewController的方法：

首先，确保你的项目已经导入了UIKit框架。
在你的UIViewController子类中，创建一个方法来实现缩放动画。以下是一个示例：

func presentViewControllerWithScaleAnimation(viewControllerToPresent: UIViewController) {
    viewControllerToPresent.modalPresentationStyle = .custom
    self.present(viewControllerToPresent, animated: true, completion: nil)
}

在你的UIViewController子类中，实现UIViewControllerTransitioningDelegate协议。这个协议允许你自定义视图控制器之间的过渡动画。

class YourViewController: UIViewController, UIViewControllerTransitioningDelegate {
    // Your view controller code
}

在你的UIViewController子类中，实现animationController(forPresented:presenting:source:)方法，该方法返回一个负责处理过渡动画的对象。在这个方法中，你可以创建一个缩放动画。

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

创建一个ScaleAnimationController类，该类遵循UIViewControllerAnimatedTransitioning协议。在这个类中，实现animateTransition(using:)方法，该方法负责执行缩放动画。

class ScaleAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
    let presenting: Bool

    init(presenting: Bool) {
        self.presenting = presenting
    }

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.3
    }

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let key = presenting ? UITransitionContextViewControllerKey.to : UITransitionContextViewControllerKey.from
        let controller = transitionContext.viewController(forKey: key)!

        if presenting {
            controller.view.transform = CGAffineTransform(scaleX: 0.001, y: 0.001)
            transitionContext.containerView.addSubview(controller.view)
        }

        let duration = transitionDuration(using: transitionContext)
        UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0.0, options: [], animations: {
            controller.view.transform = self.presenting ? CGAffineTransform(scaleX: 1.0, y: 1.0) : CGAffineTransform(scaleX: 0.001, y: 0.001)
        }) { _ in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        }
    }
}