Xamarin Forms Save Image to Gallery/Album (Android/iOS)

Create the IMediaService Interface and add following code.

IMediaService.cs

using System;
using System.Collections.Generic;
using System.Text;
 
namespace Mechat.Services
{
    public interface IMediaService
    {
        void SaveImageFromByte(byte[] imageByte,string filename);
    }
}

Now Implement this interface in Platform-specific
Xamarin.Android Project
Create the MediaService.cs Class that Implement IMediaService Interface.

MediaService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Mechat.Droid.Services;
using Mechat.Services;
using Plugin.CurrentActivity;
using Xamarin.Forms;
 
[assembly: Xamarin.Forms.Dependency(typeof(MediaService))]
namespace Mechat.Droid.Services
{
  public class MediaService : IMediaService
    {
        Context CurrentContext => CrossCurrentActivity.Current.Activity;
        public void SaveImageFromByte(byte[] imageByte,string fileName)
        {
            try
            {
                Java.IO.File storagePath = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryPictures);
                string path = System.IO.Path.Combine(storagePath.ToString(), fileName);
                System.IO.File.WriteAllBytes(path, imageByte);
                var mediaScanIntent = new Intent(Intent.ActionMediaScannerScanFile);
                mediaScanIntent.SetData(Android.Net.Uri.FromFile(new Java.IO.File(path)));
                CurrentContext.SendBroadcast(mediaScanIntent);
            }
            catch (Exception ex)
            {
 
            }
        }
    }
}

Note:   For accessing the CurrentContext  Install the NuGet Package (Plugin.CurrentActivity) from NuGet Package Manager  Also check for the external storage permission.

Xamarin.iOS Project
Create the MediaService.cs Class that Implement IMediaService Interface.

MediaService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Foundation;
using Mechat.iOS.Services;
using Mechat.Services;
using UIKit;
[assembly: Xamarin.Forms.Dependency(typeof(MediaService))]
namespace Mechat.iOS.Services
{
    public class MediaService : IMediaService
    {
        public void SaveImageFromByte(byte[] imageByte,string fileName)
        {
            var imageData = new UIImage(NSData.FromArray(imageByte));
            imageData.SaveToPhotosAlbum((image, error) =>
            {
                //you can retrieve the saved UI Image as well if needed using  
                //var i = image as UIImage;  
                if (error != null)
                {
                    Console.WriteLine(error.ToString());
                }
            });
        }
    }
 
}

How to use in Xamarin.Forms
From the code-behind side, you can call the Interface method SaveImageFromByte to save image in Gallery.

use dependency service to save image.

DependencyService.Get<IMediaService>().SaveImageFromByte(fileName, imageBytes);