How do I toggle the other menu items off? macOS - Xamarin Forms (Visual Studio for Mac)

Question

Come up with this so far:

    public void appearanceAuto(NSObject sender)
    {
        ((NSMenuItem)sender).State = NSCellStateValue.On;

        Application.Current.UserAppTheme = OSAppTheme.Unspecified;
        Preferences.Set("AppTheme", (int)OSAppTheme.Unspecified, "Global");
        window.Appearance = null;
    }

    [Action("appearanceLight:")]
    public void appearanceLight(NSObject sender)
    {
        ((NSMenuItem)sender).State = NSCellStateValue.On;

        Application.Current.UserAppTheme = OSAppTheme.Light;
        window.Appearance = NSAppearance.GetAppearance(NSAppearance.NameAqua);
        Preferences.Set("AppTheme", (int)OSAppTheme.Light, "Global");
    }

    [Action("appearanceDark:")]
    public void appearanceDark(NSObject sender)
    {
        ((NSMenuItem)sender).State = NSCellStateValue.On;

        Application.Current.UserAppTheme = OSAppTheme.Dark;
        window.Appearance = NSAppearance.GetAppearance(NSAppearance.NameDarkAqua);
        Preferences.Set("AppTheme", (int)OSAppTheme.Dark, "Global");
    }

It sets the check item correctly but I don't know get to get at the other two menu items to turn theirs off?

---

I managed to consolidate the actions into one like this:

    [Action("appearanceChanged:")]
    public void appearanceChanged(NSObject sender)
    {
        var menuItem = (NSMenuItem)sender;
        if (menuItem == null)
            return;

        NSAppearance appearance = null;
        OSAppTheme theme = OSAppTheme.Unspecified;

        var identifier = menuItem.Identifier;
        if (identifier == "appearanceDark")
        {
            appearance = NSAppearance.GetAppearance(NSAppearance.NameDarkAqua);
            theme = OSAppTheme.Dark;
        }
        else if (identifier == "appearanceLight")
        {
            appearance = NSAppearance.GetAppearance(NSAppearance.NameAqua);
            theme = OSAppTheme.Light;
        }

        window.Appearance = appearance;
        Application.Current.UserAppTheme = theme;
        Preferences.Set("AppTheme", (int)theme, "Global");

        menuItem.State = NSCellStateValue.On;
    }
}

This article helped me.

This answer to a similar question on StackOverflow shows how to do it by having a IBOutlet and using that to loop the menu items. But I am not doing this in Xcode. I am doing this in Visual Studio for Mac and I don't know how to do that bit.

I see this tutorial explain about using IBAction but it refers to connection into ViewController.h and my MacOS project does not have such a file.

For some reason, when I try to CONTROL + Drag it only wants to make a IBAction and not a IBOutlet:

Answer 1

I have now found the answer to this issue. Firstly, I did not have to actually set the State inside my action handler. It could be done inside the validateMenuItem event handler instead (which I was lacking).

I had to open my menu in Xcode first and assign the Tag property for each menu item. Then I was able to do the following:

[Export("validateMenuItem:")]
public bool validateMenuItem(NSMenuItem menuItem)
{
    switch(menuItem.Tag)
    {
        case 1000:
            if (Application.Current.UserAppTheme == OSAppTheme.Unspecified)
                menuItem.State = NSCellStateValue.On;
            else
                menuItem.State = NSCellStateValue.Off;
            break;
        case 1001:
            if (Application.Current.UserAppTheme == OSAppTheme.Light)
                menuItem.State = NSCellStateValue.On;
            else
                menuItem.State = NSCellStateValue.Off;
            break;
        case 1002:
            if (Application.Current.UserAppTheme == OSAppTheme.Dark)
                menuItem.State = NSCellStateValue.On;
            else
                menuItem.State = NSCellStateValue.Off;
            break;
    }

    return true;
}

Works well!