Question

我想在应用程序收到的每个推送消息之后呈现一个modalviewcontroller：“应用程序：（UIApplication *）应用程序didReceiveRemoteNotification：（NSDictionary *）userInfo”

我给出了这样的viewcontroller：

ReleaseViewController *viewController = [[ReleaseViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:viewController];
[self.window.rootViewController presentModalViewController:navController animated:YES];

所以当另一个push-message到来并且旧的ModalViewController仍然可见时，我想在旧的上呈现一个新的modalviewcontroller。但它不起作用。没有发生任何事情，控制台只是说（我认为这是iOS 6 Beta的调试信息）：

Warning: Attempt to present <UINavigationController: 0x1dde6c30> on <UINavigationController: 0x1dd73c00> whose view is not in the window hierarchy!

我做错了什么？

PS：我不想解散旧的ViewController，我希望它们能够堆叠。

谢谢！

Answer 1

您可以获得视图控制器的顶部，然后从该顶视图控制器中显示一个新模态

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
    if (rootViewController.presentedViewController == nil) {
        return rootViewController;
    }

    if ([rootViewController.presentedViewController isMemberOfClass:[UINavigationController class]]) {
        UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
        UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
        return [self topViewController:lastViewController];
    }

    UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
    return [self topViewController:presentedViewController];
}

你可以用rootViewController调用这个方法是window的rootViewController

Answer 2

Full Decent很接近，但有一些错误导致你在某些情况下返回错误的视图控制器。这是一个更正版本。

private func topViewController(rootViewController: UIViewController) -> UIViewController {
    var rootViewController = UIApplication.sharedApplication().keyWindow!.rootViewController!
    repeat {
        guard let presentedViewController = rootViewController.presentedViewController else {
            return rootViewController
        }

        if let navigationController = rootViewController.presentedViewController as? UINavigationController {
            rootViewController = navigationController.topViewController ?? navigationController

        } else {
            rootViewController = presentedViewController
        }
    } while true
}

在appdelegate中呈现多个模态视图

2 个答案: