iOS中实现转场动画（swift实现）

所谓转场动画，就是一个控制器的view切到另一个控制器的view上过程中过的动画效果。本例子是实现了在导航控制器的titleView边上慢慢弹出一个控制器。

专场前.png

)

专场后.png

首先自定义一个animator类。在需要转场的控制器内，设置代理

 //需要设置转场动画的控制器titleViewVc.transitioningDelegate = aniamator//这里的animator是animator的实例

下面是animator类中的代码

class animatorTool: NSObject {
    lazy var isPresent = false
    var callBack : ((isPresented:Bool)->())?//向外界传递动画是否正在显示
    
    init(callBack : ((isPresented:Bool)->())) {
        self.callBack = callBack
    }//自定义构造方法，便于给闭包赋值
}
extension animatorTool:UIViewControllerTransitioningDelegate{
    func presentationControllerForPresentedViewController(presented: UIViewController, presentingViewController presenting: UIViewController, sourceViewController source: UIViewController) -> UIPresentationController? {
        return AWYPresentationController(presentedViewController: presented, presentingViewController: presenting)//AWYPresentationController是自定义继承自UIPresentationController的类，是为了设置modal出来的vc的view的大小
    }
    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        isPresent = true
        self.callBack!(isPresented: isPresent)
        return self
    }
    
    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        isPresent = false
        self.callBack!(isPresented: isPresent)
        return self
    }
}

extension animatorTool:UIViewControllerAnimatedTransitioning{
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return 0.5//动画时长
    }
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        isPresent ?animatetransitionForPresented(transitionContext) : animatetransitionForDismissed(transitionContext)
    }
    
    func animatetransitionForPresented(transitonContext:UIViewControllerContextTransitioning){
        let aimView =  transitonContext.viewForKey(UITransitionContextToViewKey)!
        transitonContext.containerView()?.addSubview(aimView)
        
        aimView.transform = CGAffineTransformMakeScale(1.0, 0.0)
        UIView.animateWithDuration(transitionDuration(transitonContext), animations: {
            aimView.layer.anchorPoint = CGPointMake(0.5, 0.0)
            aimView.transform = CGAffineTransformIdentity
        }) { (_) in
            transitonContext.completeTransition(true)
        }
    }
    
    func animatetransitionForDismissed(transitonContext:UIViewControllerContextTransitioning){
        let aimView =  transitonContext.viewForKey(UITransitionContextFromViewKey)!
        transitonContext.containerView()?.addSubview(aimView)
        
        
        UIView.animateWithDuration(transitionDuration(transitonContext), animations: {
            aimView.layer.anchorPoint = CGPointMake(0.5, 0.0)
            aimView.transform = CGAffineTransformMakeScale(1.0, 0.001)//留一点值，这样会有动画效果
        }) { (_) in
            transitonContext.completeTransition(true)
        }
        
    }
    
    
}