Question

我已经在我的UIViewController里面的viewdidload方法中调用了以下代码。

在appdelegate中我有一个UINavigationController，它用上面提到的控制器实例化，然后UINavigationController被放在一个UITabViewController中，而UITabViewController又被指定为rootviewcontroller。

在控制器内我正在进行异步Web调用以获取数据来填充表，如果我使用加载视图代码来显示活动指示器，我会在monotouch中收到以下警告。

应用程序在应用程序启动结束时应具有根视图控制器

public class LoadingView : UIAlertView
{
    private UIActivityIndicatorView _activityView;

    public void ShowActivity (string title)
    {
        Title = title;

        this.Show();
        // Spinner - add after Show() or we have no Bounds.
        _activityView = new UIActivityIndicatorView (UIActivityIndicatorViewStyle.WhiteLarge);
        _activityView.Frame = new RectangleF ((Bounds.Width / 2) - 15, Bounds.Height - 50, 30, 30);
        _activityView.StartAnimating ();
        AddSubview (_activityView);

    }

    public void Hide ()
    {
        DismissWithClickedButtonIndex (0, true);
    }
}

任何指针都会感激不尽。

编辑：我已经设置了根视图控制器。

window = new UIWindow (UIScreen.MainScreen.Bounds);
        window.RootViewController = tabController;

完整的appDelegate代码：

public override bool FinishedLaunching (UIApplication app, NSDictionary options)
        {
            // create a new window instance based on the screen size
            window = new UIWindow (UIScreen.MainScreen.Bounds);

            tabController = new UITabBarController();

            jobsNavigationController = new UINavigationController(new JobsController());
            jobsNavigationController.NavigationBar.BarStyle = UIBarStyle.Black;
            jobsNavigationController.TabBarItem.Image = UIImage.FromFile("Images/briefcase.png");
            jobsNavigationController.TabBarItem.Title = "Current Positions";

            myAccountNavigationController = new UINavigationController(new LoginDialogViewController());
            myAccountNavigationController.NavigationBar.BarStyle = UIBarStyle.Black;
            myAccountNavigationController.TabBarItem.Image = UIImage.FromFile("images/man.png");
            myAccountNavigationController.TabBarItem.Title = "My Account";

            tabController.SetViewControllers(new UIViewController[] { jobsNavigationController,myAccountNavigationController,new SettingsDialogViewController()},false);

            window.RootViewController = tabController;

            // make the window visible
            window.MakeKeyAndVisible (); 
            return true;
        }

Answer 1

要避免此警告（在iOS5中）并保持iOS 4.x兼容性，您可以在FinishedLaunching方法中执行以下操作：

if (UIDevice.CurrentDevice.CheckSystemVersion (5, 0))
    window.RootViewController = navigation; 
else
    window.AddSubview (navigation.View);

查看here以获取更完整的样本。

Answer 2

window.AddSubview（tabcontroller.view）;

解决了这个问题，奇怪的是我不再设置rootviewcontroller了。

Monotouch异步并显示活动指示器

2 个答案: