Xamarin.IOS : MVVMCross Passing parameter from view to ViewModel

Question

I am using MVVMCross for my xamarin ios project. From my custom cell view, I want to pass a parameter to its view model. is it possible using MVVMCross?

I tried using CommandParameter property but it didn't work. Is it possible to pass parameters from view to viewmodel, If yes can someone provide a snippet?

Thank you

Update

My cell has button and on button click I want to know the cell index of the button being clicked to perform the operation. I am using the following code to do that.

this.DelayBind(() =>
{
    var bSet = this.CreateBindingSet<MyeCell, SomeViewModel>();
    bSet.Bind(cellIndex).To(vm => vm.index);
    bSet.Bind(UserPostBtn).To(vm => vm.EditPhotoCommand);
    bSet.Apply();
});

I tried using delaybind to connect view and viewmodel but on button clickm I am getting the following error:

invalid mode 'kCFRunLoopCommonModes' provided to CFRunLoopRunSpecific - break on _CFRunLoopError_RunCalledWithInvalidMode to debug. This message will only appear once per execution.

Do you want to pass the parameter on clicking the cell? Could you perhaps provide some code so we can see what you want to pass to your view model. — Plac3Hold3r

Plac3Hold3r Plac3Hold3r · Accepted Answer · 2016-12-28T18:42:56

You should be able to pass parameters to your ViewModel via a command using the MvxCommandParameterValueConverter.

String name approach:

bSet
    .Bind(UserPostBtn)
    .To(vm => vm.EditPhotoCommand)
    .WithConversion("CommandParameter", cellIndex);

Typed name approach:

bSet
    .Bind(UserPostBtn)
    .To(vm => vm.EditPhotoCommand)
    .WithConversion(new MvxCommandParameterValueConverter(), cellIndex);

Extension method approach:

bSet
    .Bind(MainButton)
    .To(vm => vm.EditPhotoCommand)
    .CommandParameter(cellIndex);

Then in your ViewModel receive the passed parameter.

IMvxCommand _editPhotoCommand;
public IMvxCommand EditPhotoCommand =>
    _editPhotoCommand ?? (_editPhotoCommand = new MvxCommand<int>(EditPhotoExecution));

private void EditPhotoExecution(int index)
{
    // do stuff
}

Update:

MvvmCross also provides an extension method, CommandParameter, that allows you to just pass in the command parameter and it will handle the creation of the MvxCommandParameterValueConverter.

Xamarin.IOS : MVVMCross Passing parameter from view to ViewModel

2 Answers