解除modalViewController的modalViewController

Question

所以我有一个UITabBarController应用程序，我想要显示一个登录页面，所以我做到了：

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(userDidLogin:) name:UserDidLoginNotification object:nil];
LoginViewController* loginViewController = [[LoginViewController alloc] init];
        self.tabBarController.selectedViewController = [self.tabBarController.viewControllers objectAtIndex:0];
        [self.tabBarController.selectedViewController presentModalViewController:loginViewController animated:NO];
        [loginViewController release];

在我的LoginViewController中，我也可以显示另一个modalViewController：

- (void) twitterLogin: (UIViewController *) askingView
{
    UIViewController *controller = [SA_OAuthTwitterController controllerToEnterCredentialsWithTwitterEngine: _twitter delegate: self];

    if (controller) {
        self.askingView = askingView;
        [askingView presentModalViewController: controller animated: YES];
    }
}

我有以下方法，其中askingView是LoginViewController，当我想要忽略它时，我会这样做：

[self.askingView dismissModalViewControllerAnimated:YES];
    [[NSNotificationCenter defaultCenter] postNotificationName:UserDidLoginNotification object:nil];

但是，这并不会忽略LoginViewController并显示UITabBarController视图。它只是关闭我在LoginvVIewController中显示的modalViewController。我在这里做错了什么？我还收到以下错误：

attempt to dismiss modal view controller whose view does not currently appear. self = <LoginViewController: 0x2aff70> modalViewController = <SA_OAuthTwitterController: 0x2d2a80>
2011-09-16 09:45:37.750 VoteBooth[4614:707] attempt to dismiss modal view controller whose view does not currently appear. self = <MainViewController: 0x29fec0> modalViewController = <LoginViewController: 0x2aff70>

Answer 1

为了消除在另一个模式视图上呈现的模式视图，您必须在父视图的父视图上调用dismissModalViewControllerAnimated:。我已经在我的一些应用程序中使用了它，它对我来说工作得很好(我花了很多时间努力弄清楚它)。下面就是我用过的代码：

[[[self parentViewController] parentViewController] dismissModalViewControllerAnimated:YES];

Answer 2

if ([self respondsToSelector:@selector(presentingViewController)]) {
    [self.presentingViewController.presentingViewController dismissModalViewControllerAnimated:YES]; // for IOS 5+
} else {
    [self.parentViewController.parentViewController dismissModalViewControllerAnimated:YES]; // for pre IOS 5
}

Answer 3

如果你有一个动态的UX，并且不知道要去多少个父级，你可以使用这个递归函数来解决这个问题。

- (void) goHome
{
    //Dismiss modal back to home page
    int numberOfVcsToDismiss = [self findRootViewController:self];
    [self dismissToRootVc:numberOfVcsToDismiss];
}

- (int) findRootViewController:(UIViewController*)vc
{
    if(vc)
    {
        return 1 + [self findRootViewController:vc.presentingViewController];
    }
    return 0;
}

- (void) dismissToRootVc:(int)count
{
    if(count == 1)
        [self dismissViewControllerAnimated:YES completion:^{}];
    if(count == 2)
        [self.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
    if(count == 3)
        [self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
    if(count == 4)
        [self.presentingViewController.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
    if(count == 5)
        [self.presentingViewController.presentingViewController.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
    //etc....
}