呈现 2 个视图控制器，但只有一个过渡

Question

我想从视图控制器“A”、第二个视图控制器“B”（带导航栏）推送，它应该显示第三个模式视图控制器“C”，它显示倒计时并自行关闭，最终显示“B ”。

我希望以模态方式呈现“C”，而不会看到“B”，当它被解除时，“B”应该已经存在了。

我一直在看这个帖子：

• Present multiple modal view controllers?
• Presenting a view controller with transparency and animation

但由于我需要推送“B”（不是模态的）我不能使用UIModalPresentationCurrentContext

我也尝试过这样做：How to push two view controllers but animate transition only for the second one?

这几乎是我想要的，但我希望“C”以模态样式呈现，例如垂直封面。

Answer 1

我终于把这两个混合在一起了：

• How to push two view controllers but animate transition only for the second one?

  NSMutableArray *controllers = [self.navigationController.viewControllers mutableCopy];
  UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
  
  MyCViewController *vcC = [storyboard instantiateViewControllerWithIdentifier:IDENTIFIER_VC];
  MyBViewController *vcB = [storyboard instantiateViewControllerWithIdentifier:IDENTIFIER_VC];
  
  [controllers addObject:vcC];
  [controllers addObject:vcB];
  
  self.navigationController.delegate = vcB;
  [self.navigationController setViewControllers:controllers animated:YES];
  

• https://www.objc.io/issues/5-ios7/view-controller-transitions/

在 vcB 中：

    -(id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
    {
        if (operation == UINavigationControllerOperationPush || operation == UINavigationControllerOperationPop) {
            MyAnimator *animator = [[MyAnimator alloc] init];
            animator.presenting = (operation == UINavigationControllerOperationPush);
            return animator;
        }
        return nil;
    }

在 MyAnimator.m 中：

-(NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.4;
}

-(void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

    [[transitionContext containerView] addSubview:toViewController.view];

    CGRect currentFrame = toViewController.view.frame;
    CGRect toFrameInitial = self.presenting ? CGRectOffset(currentFrame, 0, CGRectGetHeight(currentFrame)) : CGRectOffset(currentFrame, 0, -CGRectGetHeight(currentFrame));
    CGRect fromFrameFinal = self.presenting ? CGRectOffset(currentFrame, 0, -CGRectGetHeight(currentFrame)) : CGRectOffset(currentFrame, 0,   CGRectGetHeight(currentFrame));

    toViewController.view.frame = toFrameInitial;
    [UIView animateWithDuration:[self    transitionDuration:transitionContext] animations:^{
        toViewController.view.frame = currentFrame;
        fromViewController.view.frame = fromFrameFinal;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}