C#•8mo ago

✅ Async app initialization fails

Hi, I tried to upgrade my app initialization steps by making them async, but I am stuck with errors I don't truly understand.

1 Reply

Ikarmus•8mo ago

public partial class App : Application
{
    internal static bool IsInitialized = false;

    public App()
    {
        CollectionView_HeaderFooterFix();
        InitializeComponent();

        MainPage = new MainNavigationPage();
    }

    internal static async Task Initialization()
    {
#if DEBUG
        Preferences.Clear();
#endif
        await CheckFirstRun();
        FileManager.ReloadMaps();
        IsInitialized = true;
    }
...

public partial class App : Application
{
    internal static bool IsInitialized = false;

    public App()
    {
        CollectionView_HeaderFooterFix();
        InitializeComponent();

        MainPage = new MainNavigationPage();
    }

    internal static async Task Initialization()
    {
#if DEBUG
        Preferences.Clear();
#endif
        await CheckFirstRun();
        FileManager.ReloadMaps();
        IsInitialized = true;
    }
...

Initialization() is called from MainNavigationPage Appearing event, because that's first place I can run async code

public partial class MainNavigationPage : NavigationPage
{
    public MapDisplayPage mapDisplay;
    private Page newPage;

    public MainNavigationPage()
    {
        mapDisplay = new();
        InitializeComponent();
        Appearing += MainNavigationPage_Appearing;
        newPage = new MapPickerPage();
    }

    private async void MainNavigationPage_Appearing(object sender, EventArgs e)
    {
        if (!App.IsInitialized)
            await App.Initialization();

        await mapDisplay.UpdateDisplay();
        await Navigation.PushAsync(newPage);
    }
}

public partial class MainNavigationPage : NavigationPage
{
    public MapDisplayPage mapDisplay;
    private Page newPage;

    public MainNavigationPage()
    {
        mapDisplay = new();
        InitializeComponent();
        Appearing += MainNavigationPage_Appearing;
        newPage = new MapPickerPage();
    }

    private async void MainNavigationPage_Appearing(object sender, EventArgs e)
    {
        if (!App.IsInitialized)
            await App.Initialization();

        await mapDisplay.UpdateDisplay();
        await Navigation.PushAsync(newPage);
    }
}

I observed code failing somewhere about CopyToAsync

    internal static async Task<bool> SaveFileAsync(Stream content, string filename, bool isUserChoosingLocation = false, string initialPath = null)
    {
        initialPath ??= FileSystem.AppDataDirectory;
        if (!filename.StartsWith('\\'))
            filename = '\\' + filename;

        if (!isUserChoosingLocation)
        {
            var opts = new FileStreamOptions()
            {
                Mode = FileMode.CreateNew,
                Access = FileAccess.Write
            };
            var x = new StreamWriter(Path.Combine(initialPath + filename), opts);

            await content.CopyToAsync(x.BaseStream);
            x.Close();
            return true;
        }

#pragma warning disable CA1416 // Validate platform compatibility (Android >= 26)
        var saveResult = await fileSaver.SaveAsync(FileSystem.AppDataDirectory, filename, content, default);
        return saveResult.IsSuccessful;
#pragma warning restore CA1416 // Validate platform compatibility
    }

    internal static async Task<bool> SaveFileAsync(Stream content, string filename, bool isUserChoosingLocation = false, string initialPath = null)
    {
        initialPath ??= FileSystem.AppDataDirectory;
        if (!filename.StartsWith('\\'))
            filename = '\\' + filename;

        if (!isUserChoosingLocation)
        {
            var opts = new FileStreamOptions()
            {
                Mode = FileMode.CreateNew,
                Access = FileAccess.Write
            };
            var x = new StreamWriter(Path.Combine(initialPath + filename), opts);

            await content.CopyToAsync(x.BaseStream);
            x.Close();
            return true;
        }

#pragma warning disable CA1416 // Validate platform compatibility (Android >= 26)
        var saveResult = await fileSaver.SaveAsync(FileSystem.AppDataDirectory, filename, content, default);
        return saveResult.IsSuccessful;
#pragma warning restore CA1416 // Validate platform compatibility
    }

I tried to execute Task.Run( async () => await Initialization()); in App constructor Tried to Wait() and GetAwaiter().GetResult(); Result property as well I need to execute this method before my App.MainPage gets assigned (also can't do it outside ctor) I'm kinda stuck because I don't want to revert my changes to previous commit better is the enemy of good Ok actually some other operation were blocking the UI

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✅ Async app initialization fails