自定义 ViewController 转场动画

效果：

f8199acb-9513-4329-9772-2d73c7104828.gif

那就拿向上滑动出现的挑选主题颜色的ColorController

要设置好的如下：

• UIViewControllerTransitioningDelegate
• UIViewControllerAnimatedTransitioning
• UIPresentationController

如下设置好present的delegate和style

    func presentColorController(){
        let colorVC = self.storyboard!.instantiateViewControllerWithIdentifier("colorVC") as! ColorViewController
        //1 设置 modal PreStyle
        colorVC.modalPresentationStyle = UIModalPresentationStyle.Custom
        
        //2 设置 transition delegate
        colorVC.transitioningDelegate = transitionDelegate
        
        //3 present controller
        self.presentViewController(colorVC, animated: true, completion: nil)
    }

transitionDelegate是用来返回：要present的controller大小和动画

class TransitionDelegate:NSObject,UIViewControllerTransitioningDelegate {
    
    //选择color View controller的动画，后面会写下这个类
    let colorAnimator = ColorAnimator()
    //设置返回 present viewController 动画的函数
    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
            colorAnimator.presenting = true
            return colorAnimator
    }
    
    //设置返回 dismiss viewController 动画的函数
    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
            colorAnimator.presenting = false
            return colorAnimator
    }
    
    //返回 viewController 的大小，后面会写下这个类
    func presentationControllerForPresentedViewController(presented: UIViewController, presentingViewController presenting: UIViewController, sourceViewController source: UIViewController) -> UIPresentationController? {
        
        let customPresent = CustomPresent.init(presentedViewController: presented,presentingViewController: presenting)
        
        return customPresent
    }
}

下面这个类是动画效果的

class ColorAnimator:NSObject, UIViewControllerAnimatedTransitioning{
    
    /*设置：1.是否presenting用来判断dismiss 或者 present Controller。
        2.动画时长，3.弹性，4.弹出的初始速度
*/
    
    var presenting = true;
    var duration = 0.5
    var spring:CGFloat = 0.5
    var springV:CGFloat = 0.2
    
    //返回 时长的函数
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return duration
    }

    //动画效果
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        
        //以下用transitionContext获取变量如名，具体作用对照下图图表
        let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
        let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
        let toView = transitionContext.viewForKey(UITransitionContextToViewKey)
        let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)
        
        let containerView = transitionContext.containerView()!
        let containerFrame = transitionContext.containerView()!.frame
        
        //简单的标志
        let viewForAnimation = presenting ? toView! : fromView!
        let orignViewAniamtion = presenting ? fromVC.view : toVC.view
        
        let animationVC = presenting ? toVC  : fromVC
        
        //设置viewController的初始位置和大小，如动画示意图解释
        let initViewHight = CGRectGetHeight(transitionContext.finalFrameForViewController(animationVC))
        
        let initViewframe = CGRect(x: 0, y: CGRectGetHeight(containerFrame), width: CGRectGetWidth(containerFrame), height: initViewHight)
        
        if presenting{
            viewForAnimation.frame = initViewframe
            //如果是preset controller 要将view加入去进行动画移动
            containerView.addSubview(viewForAnimation)
        }
        
        //执行弹性动画
        UIView.animateWithDuration(self.transitionDuration(transitionContext), delay: 0, usingSpringWithDamping: spring, initialSpringVelocity: springV, options: .TransitionCurlUp, animations: { () in
            if(self.presenting){
            // present controller的结束位置
                viewForAnimation.frame = transitionContext.finalFrameForViewController(animationVC)
                orignViewAniamtion.frame.origin.y -= CGRectGetHeight(viewForAnimation.bounds)
            }else{
            //dismiss controller的结束位置
                viewForAnimation.frame = initViewframe
                orignViewAniamtion.center.y += CGRectGetHeight(viewForAnimation.bounds)
            }
            }){ h in
                if !self.presenting {
                    // 结束后如果是dissmiss controller的话要将之前的view移走
                    viewForAnimation.removeFromSuperview()
                }
                transitionContext.completeTransition(true)
            }
        
    }
}

图片：

• transitioncontext
  就是存储着动画用到的两个viewController的信息，如图：

• toView 和 fromView是不同状态下代表着controller的view

• 动画示意图

---

官方文档关于Presenting和Presented的解释,presenting view controller就是已经存在的view controller，而presented view controller则是将要present或者 dismissed的controller，并且这种关系会持续到presented view controller dissmissed为止.

---

最后一个调整要present 的controller的类

class CustomPresent: UIPresentationController {
    
    
    var dimingView:UIView!
    
    //设置最终viewController的位置和大小
    override func frameOfPresentedViewInContainerView() -> CGRect {
        
        let xOffset = 0
        let yOffset =  2 * CGRectGetHeight(containerView!.bounds) / 3
        let viewWidth = CGRectGetWidth(containerView!.bounds)
        let viewHight = 1 * CGRectGetHeight(containerView!.bounds) / 3
        return CGRectMake(xOffset, yOffset, viewWidth, viewHight)
        
    }
    
    // 初始化dimingView
    override init(presentedViewController: UIViewController, presentingViewController: UIViewController) {
        super.init(presentedViewController: presentedViewController, presentingViewController: presentingViewController)
        self.dimingView = UIView()
        self.dimingView.backgroundColor = UIColor(white: 0.0, alpha: 0.4)
        self.dimingView.alpha = 0
    }
    
    
    // present Controller 开始时执行的函数，用来动画diming view模糊背景
    override func presentationTransitionWillBegin() {
        //插入diming view
        let containerView = self.containerView!
        self.dimingView.frame = containerView.bounds
        self.dimingView.alpha = 0
        containerView.insertSubview(self.dimingView, atIndex: 0)
        
        //动画dimming view
        presentedViewController.transitionCoordinator()?.animateAlongsideTransition({
            i  in
            self.dimingView.alpha = 1.0
            }, completion: nil)
    }
    
    //present 动画结束
    override func presentationTransitionDidEnd(completed: Bool) {
        // 如果是突然中断则，移除diming view
        if(!completed){
            self.dimingView.removeFromSuperview()
        }
    }
    
    //dismiss 动画
    override func dismissalTransitionWillBegin() {
        presentedViewController.transitionCoordinator()?.animateAlongsideTransition({
            i in
            self.dimingView.alpha = 0.0
            }, completion: nil)
    }
    
    //dismiss 动画结束
    override func dismissalTransitionDidEnd(completed: Bool) {
    //如果dismiss成功则移除 dimingView
        if(completed){
            self.dimingView.removeFromSuperview()
        }
    }
    
}

像以上做的好处是，写好的动画和个性化present可以很好地抽象起来。如果别人要用到。直接复制粘贴，再将transitionDelegate赋值就可以达到同样的效果了。

这个 项目 这个文件用到了这技术

• [参考教程][6]
  [6]: http://www.appcoda.com/presentation-controllers-tutorial/