通常情况下 模态弹出的控制器是从底部向上弹出的 如果想要实现从顶部慢慢向下展开的效果 就在UIViewControllerTransitioningDelegate中,重写animationForPresentedController 和 animationControllerForDismissedController方法,分别负责转场如何出现和消失
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
func animationControllerForDismissController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
要实现以上自定义转场动画 须遵守以下协议
extension myViewController : UIViewControllerAnimatedTransitioning {
func transitionDuration(transitionContext: UIViewControllerContextTransition?) -> NSTimeInterval{
//用于告诉系统展现和消失的动画时长
return 3
}
func animateTransition(transitionContext: UIViewControllerContextTransiting){
//专门用于管理modal如何展现和消失的,无论是展现还是消失都调用该方法,只要实现了这个代理方法,那么系统就不会再有默认的动画了 也就是默认的modal从下至上的移动系统不再帮我们添加了,所有的动画操作都需要我们自己实现,包括需要展现的视图也需要我们自己添加到容器视图上
//通过toViewKey取出的就是toVC对应的view
guard let toView = transitionContext.viewControllerForKey(UITransitionContextToViewKey) else {
return //因为toView是可选值
}
//通过fromViewKey取出的就是fromVC对应的view
let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey )
//将需要弹出的控制器添加到containerView上
transitionContext.containerView()?.addSubview(toView)
//执行动画 向下展开
toView.transform = CGAffineTransformMakeScale(1.0, 0.0)
//设置锚点
toView.layer.anchorPoint = CGPoint(x:0.5,y:0)
UIView.animateWithDuration(2.0, animation: { () -> Void in
toView.transform = CGAffineTransformIdentity
}) { (_) -> Void in
transitionContext.completeTransition(true)
}
}
}
