Question

我正在使用具有不同Controller的UINavigationController。我已从导航中覆盖了BackButton。在某些情况下，如果点按了RootController，我想跳转到BackButton。

但在这种情况下，用户跳回，但整个视图为空。这种行为很奇怪，我不知道为什么。有人可以帮帮我吗。

要转到RootController我会执行以下操作。

if([self.tempnavigationInfo.refkey isEqual:@"main"]){
    [self.navigationController popToRootViewControllerAnimated:NO];
}

对于我已实现此处理程序的BackButton：

@implementation UINavigationController (ShouldPopOnBackButton)

- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {

    if([self.viewControllers count] < [navigationBar.items count]) {
        return YES;
    }

    BOOL shouldPop = YES;
    UIViewController* vc = [self topViewController];
    if([vc respondsToSelector:@selector(navigationShouldPopOnBackButton)]) {
        shouldPop = [vc navigationShouldPopOnBackButton];
    }

    if(shouldPop) {
        dispatch_async(dispatch_get_main_queue(), ^{
            [self popViewControllerAnimated:YES];
        });
    } else {
        // Workaround for iOS7.1
        for(UIView *subview in [navigationBar subviews]) {
            if(subview.alpha < 1.) {
                [UIView animateWithDuration:.25 animations:^{
                    subview.alpha = 1.;
                }];
            }
        }
    }

    return NO;
}

在ViewController中，我这样处理：

-(BOOL) navigationShouldPopOnBackButton {
 if (self.backConfirmation != nil
              && self.backConfirmation.navigation != nil
              && self.backConfirmation.confirmation == nil){
        [[NSNotificationCenter defaultCenter] postNotificationName:@"gotoWithoutConfirmation" object:self.backConfirmation.navigation];
        return NO;
    }
    return YES;
}

在我的MainController中，我捕获通知并使用上面的“popToRoot”逻辑调用该方法：

-(void) handleNotificationFromFormView:(NSNotification*) notification
{
    if([notification.name isEqualToString:@"gotoWithoutConfirmation"]){
        self.tempnavigationInfo = (NavigationInfo*)notification.object;
        [self goBackTo];
}

Answer 1

万一其他人到了这里-我有一个类似的问题使我有些困惑-原来是因为我正在使用自定义转换，将root vc的内容移出了屏幕。弹出根目录而未指定用于反转翻译的过渡，这意味着根目录随屏幕内容一起返回-不会自动重置为默认状态。

例如-如果您使用这样的UINavigationControllerDelegate设置自定义过渡：

class NavigationControllerDelegate: NSObject, UINavigationControllerDelegate {

 func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {

    if let _ = fromVC as? FirstVC, let _ = toVC as? SecondVC {
      return SlideTransitionAnimator(direction: .left)
    } 
}

和您的过渡类对rootViewController进行了一些转换-例如，就我而言，将其移出屏幕：

class SlideTransitionAnimator: NSObject, UIViewControllerAnimatedTransitioning {
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {

    guard let fromView = transitionContext.view(forKey: .from),
      let toView =  transitionContext.view(forKey: .to) else {return }

    let containerView = transitionContext.containerView
    containerView.addSubview(toView)
    switch direction  {
      case .left:
        toView.frame.origin.x = toView.frame.size.width
      default:
        toView.frame.origin.x = -toView.frame.size.width
    }

    UIView.animate(withDuration: 1,delay: 0, options: .curveEaseInOut,
                   animations: {
                     fromView.alpha = 0
                     switch self.direction  {
                       case .left:
                         fromView.frame.origin.x -= fromView.frame.size.width
                       default:
                         fromView.frame.origin.x += fromView.frame.size.width
                     }
                     toView.alpha = 1.0
                     toView.frame.origin.x = 0
    },
                   completion: { _ in
                     transitionContext.completeTransition(true)
    })

  }
}

如果在调用popToRootViewController时不反转动画或重置动画，则最终可能会看到空的根视图控制器。

popToRootViewController视图为空后，不知道原因

1 个答案: