1.簡單push動畫和present動畫

[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]; 

//系統的API
- (void)addAnimation:(CAAnimation *)anim forKey:(nullable NSString *)key;

自定義push動畫，然后在push時添加到navigationController中
CATransition -> CAAnimation -> NSObject

    CATransition *transition = [CATransition animation];
    transition.duration = 0.6;
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
    
    //動畫類型，一下是系統API的介紹
    /* The name of the transition. Current legal transition types include
     * `fade', `moveIn', `push' and `reveal'. Defaults to `fade'. */
    transition.type = @"";

    /*私有API
     cube                   立方體效果
     pageCurl               向上翻一頁
     pageUnCurl             向下翻一頁
     rippleEffect           水滴波動效果
     suckEffect             變成小布塊飛走的感覺
     oglFlip                上下翻轉
     cameraIrisHollowClose  相機鏡頭關閉效果
     cameraIrisHollowOpen   相機鏡頭打開效果
     */

最后push或present頁面就可以完成動畫

2.非交互式轉場動畫

1.需要當前的navigationController遵循<UINavigationControllerDelegate>并實現其代理方法

-  (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC 

可以在此代理方法中判斷當前是push還是pop

2.我們需要在代理方法中返回一個UIViewControllerAnimatedTransitioning對象，于是我們創建一個類繼承自NSObject，遵循<UIViewControllerAnimatedTransitioning>協議，并實現其代理方法
代理方法主要有以下2個

// 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.
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;

// This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

第一個方法將返回動畫的時長
第二個方法將具體實現動畫

//轉場過渡的容器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:^{
        //具體的動畫實現

  } completion:^(BOOL finished) {
        BOOL wasCancelled = [transitionContext transitionWasCancelled];
        //設置transitionContext通知系統動畫執行完畢
        [transitionContext completeTransition:!wasCancelled];
}];

實現酷狗的轉場動畫
分別創建兩個類繼承自NSObject，遵循<UIViewControllerAnimatedTransitioning>協議，來實現push和pop的動畫效果

1.push動畫,將將push的view做仿射變換

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext;

//轉場過渡的容器view
UIView *containerView = [transitionContext containerView];
//ToVC
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *toView = toViewController.view;
[containerView addSubview:toView];

//將toView繞原點旋轉45度
toView.transform = 

2.pop動畫同理

3.交互式轉場動畫

<UINavigationControllerDelegate>實現其代理方法

- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                          interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController

實現這個方法，系統轉場時，就會知道當前是否有交互式的轉場，有便執行交互轉場，無則執行普通自定義的轉場動畫
UIPercentDrivenInteractiveTransition類是系統定義的，他遵循UIViewControllerInteractiveTransitioning協議
此類提供了了以下方法

// These methods should be called by the gesture recognizer or some other logic
// to drive the interaction. This style of interaction controller should only be
// used with an animator that implements a CA style transition in the animator's
// animateTransition: method. If this type of interaction controller is
// specified, the animateTransition: method must ensure to call the
// UIViewControllerTransitionParameters completeTransition: method. The other
// interactive methods on UIViewControllerContextTransitioning should NOT be
// called. If there is an interruptible animator, these methods will either scrub or continue 
// the transition in the forward or reverse directions.

- (void)updateInteractiveTransition:(CGFloat)percentComplete;
- (void)cancelInteractiveTransition;
- (void)finishInteractiveTransition;

根據pop時傳遞的手勢信息來計算滑動百分比，從而完成交互動畫和取消動畫