1. 简单push动画和present动画
[self.navigationController.view.layer addAnimation:[self pushAnimation] forKey:@""];
[self.navigationController pushViewController:[] animated:NO];
[self.view.window.layer addAnimation:[self presentAnimation] forKey:nil];
[self presentViewController:second animated:NO completion:nil]; 
//系统的API
- (void)addAnimation:(CAAnimation *)anim forKey:(nullable NSString *)key;
自定义push动画,然后在push时添加到navigationController中 CATransition -> CAAnimation -> NSObject
    CATransition *transition = [CATransition animation];
    transition.duration = 0.6;
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
    
    //动画类型,一下是系统API的介绍
    /* The name of the transition. Current legal transition types include
     * `fade', `moveIn', `push' and `reveal'. Defaults to `fade'. */
    transition.type = @"";
    /*私有API
     cube                   立方体效果
     pageCurl               向上翻一页
     pageUnCurl             向下翻一页
     rippleEffect           水滴波动效果
     suckEffect             变成小布块飞走的感觉
     oglFlip                上下翻转
     cameraIrisHollowClose  相机镜头关闭效果
     cameraIrisHollowOpen   相机镜头打开效果
     */
最后push或present页面就可以完成动画
2.非交互式转场动画
- 1.需要当前的navigationController遵循并实现其代理方法 
//可以在此代理方法中判断当前是push还是pop
-  (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC 
- 2.我们需要在代理方法中返回一个UIViewControllerAnimatedTransitioning对象,于是我们创建一个类继承自NSObject,遵循协议,并实现其代理方法 代理方法主要有以下2个 
// This is used for percent driven interactive transitions, as well as for
// container controllers that have companion animations that might need to
// synchronize with the main animation.
//返回动画的时长
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;
// This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.
//实现具体的动画
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;
//转场过渡的容器view
UIView *containerView = [transitionContext containerView];
//FromVC
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIView *fromView = fromViewController.view;
//ToVC
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *toView = toViewController.view;
NSInteger toVCCount = [toViewController.navigationController.viewControllers indexOfObject:toViewController];
NSInteger fromVCCount = [fromViewController.navigationController.viewControllers indexOfObject:fromViewController];
if (toVCCount > fromVCCount) {
   //push
    [containerView addSubview:fromView];
    [containerView addSubview:toView];
}
else{
  //pop
    [containerView addSubview:toView];
    [containerView addSubview:fromView];
}
[UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        //具体的动画实现
  } completion:^(BOOL finished) {
        BOOL wasCancelled = [transitionContext transitionWasCancelled];
        //设置transitionContext通知系统动画执行完毕
        [transitionContext completeTransition:!wasCancelled];
}];
实现酷狗的转场动画
*分别创建两个类继承自NSObject,遵循
- 1.push动画,将将push的view做仿射变换
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext;
//转场过渡的容器view
UIView *containerView = [transitionContext containerView];
//ToVC
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *toView = toViewController.view;
[containerView addSubview:toView];
//将toView绕原点旋转45度
toView.transform = 
- 2.pop动画同理
- 3.交互式转场动画