Fluent binding and conversions

Question

When following the Tutorial for TipCalc's iOS UI, I noticed that the binding method described is obsolete(?) and decided to start using Fluent bindings like described here.

Everything gone fine except for one thing: the iOS slider on the tutorial uses a float value between 0 and 1, and the view model uses a int between 0 and 100. So, obviously, I need a conversion here.

Since it's a two-way-binding, how can bind it to be converted for ViewModel -> View and View -> ViewModel? (ideally with fluent binding)

Also, I'd like to know how can I register a conversion under a "name" to later reuse it. Like it seems to be done on this line.

I tried to search on MvvmCross repos for these named conversions but I didn't find anything like a list of the available conversions, there is such a thing?

Thanks a lot for any help!!

Answer 1

I noticed that the binding method described is obsolete(?)

The message attached to that method is:

   [Obsolete("Please use SourceDescribed or FullyDescribed instead")]

So use SourceDescribed if you only want to describe the source, or FullyDescribed if you want to describe the source and target.

   set.Bind(label).For(l => l.Text).SourceDescribed("'Hello ' + SourceText");

or:

   set.Bind(label).FullyDescribed("Text 'Hello ' + SourceText");

Since it's a two-way-binding, how can bind it to be converted for ViewModel -> View and View -> ViewModel?

Two way converters implement both Convert and ConvertBack.

For example - see:

public class TwoWayConverter : MvxValueConverter<double, string>
{
    protected override string Convert(double value, Type targetType, object parameter, CultureInfo culture)
    {
        return (value*value).ToString();
    }

    protected override double ConvertBack(string value, Type targetType, object parameter, CultureInfo culture)
    {
        double doubleValue;
        double.TryParse(value, out doubleValue);
        return Math.Sqrt(doubleValue);
    }
}

from https://github.com/MvvmCross/MvvmCross-Tutorials/blob/master/ValueConversion/ValueConversion.Core/Converters/Converters.cs

I'd like to know how can I register a conversion under a "name" to later reuse it

The names are registered by reflection and convention - see a full description in https://github.com/MvvmCross/MvvmCross/wiki/Value-Converters#referencing-value-converters-in-touch-and-droid

a list of the available conversions

MvvmCross doesn't provide many by default - these are mainly app things.

The only built-in converters that I know of are for:

• color
• visible
• language
• command parameter

All of these are discussed in https://github.com/MvvmCross/MvvmCross/wiki/Value-Converters#the-mvx-visibility-valueconverters