ImagePicker MainActivity Instance is not defined - xamarin

Question

Followed the below link in adding the ImagePicker
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/dependency-service/photo-picker
Here, for Android Implementation the issue is Instance is not defined in the MainActivity.cs
[assembly: Dependency(typeof(PicturePickerImplementation))]
namespace DependencyServiceSample.Droid
{
public class PicturePickerImplementation : IPicturePicker
{
public Task<Stream> GetImageStreamAsync()
{
// Define the Intent for getting images
Intent intent = new Intent();
intent.SetType("image/*");
intent.SetAction(Intent.ActionGetContent);
// Start the picture-picker activity (resumes in MainActivity.cs)
MainActivity.Instance.StartActivityForResult(
Intent.CreateChooser(intent, "Select Picture"),
MainActivity.PickImageId);
// Save the TaskCompletionSource object as a MainActivity property
MainActivity.Instance.PickImageTaskCompletionSource = new TaskCompletionSource<Stream>();
// Return Task object
return MainActivity.Instance.PickImageTaskCompletionSource.Task;
}
}
}
And the MainActivity doesn't have the Instance Field, Is there an alternate way to get the instance?
public class MainActivity : FormsAppCompatActivity
{
...
// Field, property, and method for Picture Picker
public static readonly int PickImageId = 1000;
public TaskCompletionSource<Stream> PickImageTaskCompletionSource { set; get; }
protected override void OnActivityResult(int requestCode, Result resultCode, Intent intent)
{
base.OnActivityResult(requestCode, resultCode, intent);
if (requestCode == PickImageId)
{
if ((resultCode == Result.Ok) && (intent != null))
{
Android.Net.Uri uri = intent.Data;
Stream stream = ContentResolver.OpenInputStream(uri);
// Set the Stream as the completion of the Task
PickImageTaskCompletionSource.SetResult(stream);
}
else
{
PickImageTaskCompletionSource.SetResult(null);
}
}
}
}

Answer 1

To the MainActivity Class add this:
internal static MainActivity Instance { get; private set; }
protected override void OnResume()
{
Instance = this;
base.OnResume();
}
also thanks to #SushiHangover's answer here for describing how to initialize the Instance object.
The documentation is missing this, most likely.

Answer 2

You are missing a static variable definition and its assignment.
Add a static var named Instance to the MainActivity class:
public static Activity Instance;
and then in the OnResume override assign it:
protected override void OnResume()
{
Instance = this;
base.OnResume();
}