XLBubbleTransition UINavigation的转场动画 项目简介
XLBubbleTransition 是一个适用于UINavigation的转场动画，在Push和Pop这两个动作时显示。使用方法：在ViewController中设置push和pop的转场动画,初始化时需要设置动画的起始范围和结束范围.self.xl_pushTranstion = [XLBubblePushTransition transitionWithAnchorRect:button.frame];
self.xl_popTranstion = [XLBubblePopTransition transitionWithAnchorRect:button.frame];
self.xl_popTranstion = [XLBubblePopTransition transitionWithAnchorRect:button.frame];