Building the ViewModel class

We will start by creating the ViewModel class, which will handle what will happen when a user taps one of the buttons. Let's set this up by going through the following steps:

1. Create a new class called  MainViewModel in the ViewModels folder.
2. Add ViewModel as a base class for MainViewModel.
3. Create a private field of the IClassifier type and call it classifier.
4. Create a constructor that has the IClassifier as a parameter.
5. Set the value of the classifier field to the value of the parameter in the constructor, as shown in the following code block:

using System.IO;
using System.Linq;
using System.Windows.Input;
using HotdogOrNot.Models;
using HotdogOrNot.Views;
using Xamarin.Forms; 

public class MainViewModel : ViewModel
{
    private IClassifier classifier;

    public MainViewModel(IClassifier classifier)
    {
        this.classifier = classifier;
    } 
}

We will use the Xam.Plugin.Media NuGet package for taking the photo and...