iOS 上的空白屏幕

Question

我有一个 Xamarin 项目，我已经从事了相当长的一段时间。 但是突然打开主界面就空白了。在 iOS 模拟器和我的 iOS 设备上。

应用构建时没有错误。我得到了启动画面，然后只是一个白色的空白屏幕。

我在带有 MVVMCross 和情节提要的 Visual Studio 15 中使用 Xamarin。

我尝试了以下方法：

1. 重置 iOS 模拟器
2. Visual Studio 中的已清理解决方案
3. 尝试将另一个故事板作为主界面

有什么想法吗？

编辑：这是我的 AppDelegate.cs 文件：

using Foundation;
using MvvmCross.Core.ViewModels;
using MvvmCross.iOS.Platform;
using MvvmCross.Platform;
using UIKit;
using Tjenester.Touch.Util;

namespace Tjenester.Touch
{
    [Register("AppDelegate")]
    public partial class AppDelegate : MvxApplicationDelegate
    {
        UIWindow _window;

        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            _window = new UIWindow(UIScreen.MainScreen.Bounds);
            var setup = new Setup(this, _window);
            setup.Initialize();

            var startup = Mvx.Resolve<IMvxAppStart>();
            startup.Start();

            _window.MakeKeyAndVisible();

            MessageService.Initialize(this);

            return true;
        }
    }
}

这是我的 CustomAppStart.cs：

using System;
using System.Threading.Tasks;
using Tjenester.Core.Helpers;
using Tjenester.Core.Services.Authentication;
using Tjenester.Core.ViewModels;
using Tjenester.Core.ViewModels.ViewModelParameters;
using Xamarin.Auth;
using Tjenester.Core;
using System.Threading;
using MvvmCross.Core.ViewModels;

/// <summary>
/// Custom Application start procedure to be fed to MvvmCross.
/// If we already have Username and Password, try login and proceed to the page.
/// TODO refactor when azure and google are added
/// </summary>
public class CustomAppStart : MvxNavigatingObject, IMvxAppStart
{

    public void Start(object hint = null)
    {
        ShowViewModel<LoginViewModel>(new LoginPageParameters() {TryLogin = true});
    }
}

这是我的 Setup.cs：

using UIKit;
using Tjenester.Core.Helpers;
using Foundation;
using Tjenester.Core.Services.Media;
using Tjenester.Touch.Services;
using Tjenester.Core.Services.Storage;
using Tjenester.Core.Services.Scripting;
using Tjenester.Core;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using Tjenester.Core.Services.Http;
using MvvmCross.Core.ViewModels;
using MvvmCross.iOS.Platform;
using MvvmCross.Localization;
using MvvmCross.Platform;
using MvvmCross.Platform.Platform;
using MvvmCross.Platform.Plugins;
using Tjenester.Touch.Services.Http;
using Tjenester.Touch.Services.Storage;

namespace Tjenester.Touch
{
    public class Setup : MvxIosSetup
    {
        private readonly UIWindow _win;
        private readonly MvxApplicationDelegate _del;

        public Setup(MvxApplicationDelegate applicationDelegate, UIWindow window)
            : base(applicationDelegate, window)
        {
            _del = applicationDelegate;
            _win = window;
        }

        protected override IMvxApplication CreateApp()
        {
            UIContext.SynchronizationContext = SynchronizationContext.Current;
            if (NSLocale.PreferredLanguages.Length > 0) {
                var pref = NSLocale.PreferredLanguages [0];
                Settings.Language = pref.Substring (0, 2);
            }
            //Mvx.LazyConstructAndRegisterSingleton<IFileUploadService, TouchFileUploadService>();
            Mvx.LazyConstructAndRegisterSingleton<IHttpClientFactory, HttpClientFactory>();
            Mvx.LazyConstructAndRegisterSingleton<IStorageService, StorageService>();
            Mvx.LazyConstructAndRegisterSingleton<IPicturePickerService, TouchPicturePickerService>();
            return new Core.App();
        }

        protected override IEnumerable<System.Reflection.Assembly> ValueConverterAssemblies
        {
            get
            {
                var toReturn = base.ValueConverterAssemblies.ToList();
                toReturn.Add(typeof(MvxLanguageConverter).Assembly);
                return toReturn;
            }
        }

        protected override IMvxPluginConfiguration GetPluginConfiguration(Type plugin)
        {
            if (plugin == typeof(Tjenester.Core.Services.Scripting.PluginLoader))
            {
                return new MvxScriptServiceConfiguration()
                    .UseDefaultScriptBindings()
                ;
            }
            return base.GetPluginConfiguration(plugin);
        }

        protected override IMvxTrace CreateDebugTrace()
        {
            return new MvxDebugTrace();
        }
    }
}

Answer 1

您能否尝试手动初始化 MvxIosViewPresenter 以获取更多信息？

因此，您必须使用以下行 (ApplicationDelegate.cs)：

_window = new UIWindow(UIScreen.MainScreen.Bounds);
var presenter = new MvxIosViewPresenter(this, _window);

var setup = new Setup(this, presenter);
setup.Initialize();

var startup = Mvx.Resolve<IMvxAppStart>();
startup.Start();

var rootViewController = new FirstView(); // You need to have created this ViewController
_window.RootViewController = rootViewController;

_window.MakeKeyAndVisible();

return true;

如果这对您有用，则表示您的情节提要尚未正确创建。您在情节提要上设计的 FirstViewController 不知道实现 MvxViewController 的类 FirstViewViewController 的“代码”版本。

想来一场狂欢，看看进展如何？这不是一个优雅的解决方案，但可以提供一些见解。