源码推荐(02.16B)：模仿简书、淘宝弹出效果动画，GIF文件生成和播放

@property (nonatomic, strong) LHCustomModalTransition *transition;
......
//---初始化要弹出跳转的视图控制器
ModalViewController *modalVC = [ModalViewController new];
//---必须强引用，否则会被释放，自定义dismiss的转场无效
self.transition = [[LHCustomModalTransition alloc]initWithModalViewController:modalVC];
//---是否可下拉收起
self.transition.dragable = YES;
modalVC.transitioningDelegate = self.transition;
//---必须添加这句.自定义转场动画
modalVC.modalPresentationStyle = UIModalPresentationCustom;