1、業務需求：點選按鈕，自定義一個模態動畫，動畫大概，把上個介面一分為二，從中間分離然後顯示模態出來的介面

import UIKit
// 列舉：present、dismiss的動畫區分
enum CNPresentOneTransitionType {
    case Present // 管理present動畫
    case Dismiss // 管理dismiss動畫

}

class CNPresnetOneTransition: NSObject,UIViewControllerAnimatedTransitioning {
    var typeT : CNPresentOneTransitionType!
    init(transitionType:CNPresentOneTransitionType) {
        super.init
 
()
        typeT = transitionType
    }
    // 動畫時間
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.25
    }
    // 做動畫需要的前後兩個檢視
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        switch typeT! {
        case CNPresentOneTransitionType.Present
 
:
            presentAnimation(transitionContext: transitionContext)
        case CNPresentOneTransitionType.Dismiss:
            dismissAnimation(transitionContext: transitionContext)
        default:
            break
        }
    }

    // 實現present動畫邏輯程式碼
    func presentAnimation(transitionContext : UIViewControllerContextTransitioning){
        let fromVC = transitionContext.viewController
 
(forKey: UITransitionContextViewControllerKey.from)

        if fromVC!.isKind(of: UINavigationController.self){
            print("sssss")
        }

        let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to) as! UINavigationController
        if toVC.isKind(of: UINavigationController.self){
            print("hhhh")
        }
        let contentView = transitionContext.containerView

        let screenWidth = UIScreen.main.bounds.size.width
        let screenHeight = UIScreen.main.bounds.size.height

        var rect0 : CGRect!
        var rect1 : CGRect!

        rect0 = CGRect(x: 0, y: 0, width: screenWidth, height: screenHeight/2)
        rect1 = CGRect(x: 0, y: screenHeight/2, width: screenWidth, height: screenWidth)


        let image0 = imageFromView(view:(fromVC?.view)!, atFrame: rect0)
        let image1 = imageFromView(view: (fromVC?.view)!, atFrame: rect1)

        let imageView0 = UIImageView(image: image0)
        let imageView1 = UIImageView(image: image1)

//        contentView.addSubview((fromVC?.view)!)

        contentView.addSubview(toVC.view)
        contentView.addSubview(imageView0)
        contentView.addSubview(imageView1)

        UIView.animate(withDuration: self.transitionDuration(using: transitionContext), animations: {
            imageView0.layer.transform = CATransform3DMakeTranslation(0, -screenHeight / 2, 0)
            imageView1.layer.transform = CATransform3DMakeTranslation(0, screenHeight / 2, 0)
        }) { (isSuccess) in
            transitionContext.completeTransition(true)
            imageView0.removeFromSuperview()
            imageView1.removeFromSuperview()
        }
    }

    //實現dismiss動畫邏輯程式碼
    func dismissAnimation(transitionContext : UIViewControllerContextTransitioning){
        let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
        let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
        let contentView = transitionContext.containerView

        let screenWidth = UIScreen.main.bounds.size.width
        let screenHeight = UIScreen.main.bounds.size.height

        var rect0 : CGRect!
        var rect1 : CGRect!

        rect0 = CGRect(x: 0, y: 0, width: screenWidth, height: screenHeight/2)
        rect1 = CGRect(x: 0, y: screenHeight/2, width: screenWidth, height: screenWidth)

        let image0 = imageFromView(view: (toVC?.view)!, atFrame: rect0)
        let image1 = imageFromView(view: (toVC?.view)!, atFrame: rect1)

        let imageView0 = UIImageView(image: image0)
        let imageView1 = UIImageView(image: image1)


//        contentView.addSubview((fromVC?.view)!)
//        contentView.addSubview((toVC?.view)!)
        contentView.addSubview(imageView0)
        contentView.addSubview(imageView1)

        toVC?.view.isHidden = true

        imageView0.layer.transform = CATransform3DMakeTranslation(0, -screenHeight / 2, 0)
        imageView1.layer.transform = CATransform3DMakeTranslation(0, screenHeight / 2, 0)

        UIView.animate(withDuration: self.transitionDuration(using: transitionContext), animations: {
            imageView0.layer.transform = CATransform3DIdentity
            imageView1.layer.transform = CATransform3DIdentity
        }) { (isSuccess) in
            transitionContext.completeTransition(true)
            toVC?.view.isHidden = false
            imageView0.removeFromSuperview()
            imageView1.removeFromSuperview()
        }
    }


    /// 截圖
    ///
    /// - Parameters:
    ///   - view: view
    ///   - atFrame: rect
    func imageFromView(view : UIView,atFrame:CGRect) -> UIImage {
        UIGraphicsBeginImageContext(view.frame.size)
        let context = UIGraphicsGetCurrentContext()
        context?.saveGState()
        UIRectClip(atFrame)
        view.layer.render(in: context!)
        let theImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return theImage!
    }
}

用法：
在你模態出來的那個介面先實現代理

UIViewControllerTransitioningDelegate

並在viewDidLoad裡面實現

        self.navigationController?.modalPresentationStyle = .custom
        self.navigationController?.transitioningDelegate = self

最後實現兩個代理

    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CNPresnetOneTransition(transitionType: CNPresentOneTransitionType.Present)
    }

    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CNPresnetOneTransition(transitionType: CNPresentOneTransitionType.Dismiss)
    }