WithConversion<...> does not appear do the same as WithConversion(new ...)

[tofutim]

Steps to reproduce 📜

1. Write a new converter, I needed a NotValueConverter, so I wrote

public class NotValueConverter : IMvxValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return !((bool)value);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return !((bool)value);
    }
}

2. In my viewController,

set.Bind(loginButton).For(v => v.Enabled).To(vm => vm.IsLoggedIn).WithConversion<NotValueConverter>();

Expected behavior 🤔

When IsLoggedIn is false, I expect my loginButton to be enabled; which I guess means that I expect that MvvmCross will automatically look for the NotValueConverter, create an instance if it doesn't yet exist, and then use that.

Actual behavior 🐛

loginButton is not enabled, not converter is never called. However, if I use

set.Bind(loginButton).For(v => v.Enabled).To(vm => vm.IsLoggedIn).WithConversion(new NotValueConverter());

it does do the right thing. Maybe I had to Mvx.Register the NotConverter? Not sure. I also want to note that I can use .WithConversion("NotConverter") if I register using

protected override void FillValueConverters(MvvmCross.Platform.Converters.IMvxValueConverterRegistry registry)
{
    base.FillValueConverters(registry);

    registry.AddOrOverwrite("NotConverter", new NotValueConverter());
}

When I register as such, .WithConversion<NotValueConverter>() still does not work.

Configuration 🔧

Version: 5.5.2

Platform:

• 📱 iOS
• 🤖 Android
• 🏁 WPF
• 🌎 UWP
• 🍎 MacOS
• 📺 tvOS
• 🐒 Xamarin.Forms

[mvanbeusekom]

@tofutim sorry for the delay in response, its been a busy few weeks for me. Anyway I found some time to look into it and I am having a hard time on reproducing the problem.

I have created a reproduction example on my own GitHub fork which can be found here: https://github.com/mvanbeusekom/MvvmCross (in the issues/2449_GenericValueConverter branch). The example are part of the Playground.iOS and Playground.Mac test projects and can be found in the RootView class in both projects. I haven't done any additional registration to get the value converters to work.

First I created a simple converter which randomly gets a color and applied the color to a label (on both iOS and MacOS application) and both work fine using the generic WithConversion<RandomColorValueConverter> method.

After that (just to be thourough) I have also added a copy of your NotValueConverter to the Playground.Mac project and applied it to the Enabled property of the "Show Child" button in the RootView class. This also seems to behave as expected (you'll manually need to change the boolean value for the IsLoggedIn property of the RootViewModel class to see both states, but both work as expected).

Maybe you can have a look at these example implementations to check for differences in your solution. If you still experience the problem please provide a minimal reproduction example we can use to further debug this issue.