swift 自定义转场 动画弹出 View

代码基于 swift 4.2

概念

自定义转场其实就是 modal控制的时候，实现UIViewControllerTransitioningDelegate转场代理

       @objc private func titleBtnClick(titleBtn:TitleButton){
        titleBtn.isSelected = !titleBtn.isSelected
        
        // 1.创建弹出的控制器
        let popoverVc = PopoverViewController()
        
        // 2.设置控制器的modal样式
        popoverVc.modalPresentationStyle = .custom
        
        // 3.设置转场的代理
        popoverVc.transitioningDelegate = popoverAnimator
      //弹出view的frame
        popoverAnimator.presentedFrame = CGRect(x: 100, y: 64, width: 180, height: 250)
        // 4弹出控制器
        present(popoverVc, animated: true, completion: nil)
        
        
    }

转场代理实现

返回一个自定义的UIPresentationController 。

import UIKit

class PopoverAnimator: NSObject {
    // MARK:- 属性
    var isPresented : Bool = false
    var presentedFrame : CGRect = CGRect.zero
}

// MARK: - 自定义转场代理
extension PopoverAnimator:UIViewControllerTransitioningDelegate{
    // 目的:改变弹出View的尺寸
    func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        let presentation = CLPresentationController(presentedViewController: presented, presenting: presenting)
        presentation.presentedFrame = presentedFrame
        return presentation
    }
    // 目的:自定义弹出的动画
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        isPresented = true
        return self
    }
    // 目的:自定义消失的动画
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        isPresented = false
        return self
    }
}
// MARK:- 弹出和消失动画代理的方法
extension PopoverAnimator : UIViewControllerAnimatedTransitioning{
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.5
    }
    /// 获取`转场的上下文`:可以通过转场上下文获取弹出的View和消失的View
    // UITransitionContextFromViewKey : 获取消失的View
    // UITransitionContextToViewKey : 获取弹出的View
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        isPresented ? animationForPresentedView(transitionContext: transitionContext) :animationForDismissedView(transitionContext: transitionContext)
    }
    /// 自定义弹出动画
    private func animationForPresentedView(transitionContext:UIViewControllerContextTransitioning){
        // 1.获取弹出的View
        let presentedView = transitionContext.view(forKey: .to)
        // 2.将弹出的View添加到transitionContext的containerView中
        transitionContext.containerView.addSubview(presentedView!)
        //设置锚点位置（缩放位置）
        presentedView?.layer.anchorPoint = CGPoint(x: 0.5, y: 0)
        // 3.执行动画
        presentedView?.transform = CGAffineTransform.init(scaleX: 1, y: 0)
        UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
            presentedView?.transform = CGAffineTransform.identity
        }) { (_) in
            // 必须告诉转场上下文你已经完成动画
            transitionContext.completeTransition(true)
        }
    }
    /// 自定义消失动画
    private func animationForDismissedView(transitionContext:UIViewControllerContextTransitioning){
        // 1.获取消失的View
        let dismissView = transitionContext.view(forKey: .from)
        
        // 2.执行动画
        
        UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
            dismissView?.transform = CGAffineTransform.init(scaleX: 1, y: 0.00001)
        }) { (_) in
            dismissView?.removeFromSuperview()
            // 必须告诉转场上下文你已经完成动画
            transitionContext.completeTransition(true)
        }
        
    }
    
}

UIPresentationController 自定义

modal 其实是先弹出一个containerView，再把要弹出的控制器加入containerView，默认弹出的控制器大小和containerView相同，所以我需要自定义UIPresentationController重新布局containerView 的子控件来实现自定义弹出控制器的大小。
需要重写containerViewWillLayoutSubviews 方法。
presented是被弹出的控制器
presentedView是被弹出的控制器的 VIew

import UIKit

class CLPresentationController: UIPresentationController {
    // MARK:- 对外提供属性
    var presentedFrame : CGRect = CGRect.zero
    private lazy  var coverView:UIView = UIView()
    override func containerViewWillLayoutSubviews() {
        super.containerViewWillLayoutSubviews()
        //弹出 view的尺寸
        presentedView?.frame = presentedFrame
        
        setupCoverView()
        
    }
}


// MARK: - 设置 UI
extension CLPresentationController{
    private func setupCoverView(){
        //底部插入蒙版
        containerView?.insertSubview(coverView, at: 0)
        // 2.设置蒙版的属性
        coverView.backgroundColor = UIColor(white: 0.8, alpha: 0.2)
        coverView.frame = containerView?.frame ?? CGRect.zero
        // 3.添加手势
        let tapGes = UITapGestureRecognizer(target: self, action: #selector(coverViewClick))
        coverView.addGestureRecognizer(tapGes)
        
    }
}
// MARK:- 事件监听
extension CLPresentationController {
    
    /// 移除 modal
    @objc private func coverViewClick() {
        presentedViewController.dismiss(animated: true, completion: nil)
    }
}