A class that retrieve the path to a local resource (video/image/audio) in phone.

PathUtils.cs

using System;
using Android.Content;
using Android.Database;
using Android.OS;
using Android.Provider;
using Java.Lang;
using Environment = Android.OS.Environment;
using String = System.String;
using Uri = Android.Net.Uri;

namespace PathUtils
{
    public static class PathUtils
    {
        public static string GetPath (Context context, Uri uri)
        {
            var isKitKat = Build.VERSION.SdkInt >= BuildVersionCodes.Kitkat;
            // DocumentProvider
            if (isKitKat && DocumentsContract.IsDocumentUri (context, uri)) {
                // ExternalStorageProvider
                if (IsExternalStorageDocument (uri)) {
                    var docId = DocumentsContract.GetDocumentId (uri);
                    var split = docId.Split (':');
                    var type = split [0];
                    if ("primary".EqualsIgnoreCase (type)) {
                        return Environment.ExternalStorageDirectory + "/" + split [1];
                    }
                }
                // DownloadsProvider
                else if (IsDownloadsDocument (uri)) {
                    var id = DocumentsContract.GetDocumentId (uri);
                    var contentUri = ContentUris.WithAppendedId (
                                         Uri.Parse ("content://downloads/public_downloads"), (long)Long.ValueOf (id));
                    return GetDataColumn (context, contentUri, null, null);
                }
                // MediaProvider
                else if (IsMediaDocument (uri)) {
                    var docId = DocumentsContract.GetDocumentId (uri);
                    var split = docId.Split (':');
                    var type = split [0];
                    Uri contentUri = null;
                    if ("image".Equals (type)) {
                        contentUri = MediaStore.Images.Media.ExternalContentUri;
                    } else if ("video".Equals (type)) {
                        contentUri = MediaStore.Video.Media.ExternalContentUri;
                    } else if ("audio".Equals (type)) {
                        contentUri = MediaStore.Audio.Media.ExternalContentUri;
                    }
                    var selection = "_id=?";
                    var selectionArgs = new []
                    {
                        split[1]
                    };
                    return GetDataColumn (context, contentUri, selection, selectionArgs);
                }
            }
            // MediaStore (and general)
            else if ("content".EqualsIgnoreCase (uri.Scheme)) {
                return GetDataColumn (context, uri, null, null);
            }
            // File
            else if ("file".EqualsIgnoreCase (uri.Scheme)) {
                return uri.Path;
            }
            return null;
        }

        private static String GetDataColumn (Context context, Uri uri, String selection,
                                            String [] selectionArgs)
        {
            ICursor cursor = null;
            var column = "_data";
            string [] projection =
                {
                column
            };
            try {
                cursor = context.ContentResolver.Query (uri, projection, selection, selectionArgs,
                    null);
                if (cursor != null && cursor.MoveToFirst ()) {
                    var columnIndex = cursor.GetColumnIndexOrThrow (column);
                    return cursor.GetString (columnIndex);
                }
            } finally {
                if (cursor != null)
                    cursor.Close ();
            }
            return null;
        }

        /**
        * @param uri The Uri to check.
        * @return Whether the Uri authority is ExternalStorageProvider.
        */

        private static bool IsExternalStorageDocument (Uri uri)
        {
            return "com.android.externalstorage.documents".Equals (uri.Authority);
        }

        /**
        * @param uri The Uri to check.
        * @return Whether the Uri authority is DownloadsProvider.
        */

        private static bool IsDownloadsDocument (Uri uri)
        {
            return "com.android.providers.downloads.documents".Equals (uri.Authority);
        }

        /**
        * @param uri The Uri to check.
        * @return Whether the Uri authority is MediaProvider.
        */

        private static bool IsMediaDocument (Uri uri)
        {
            return "com.android.providers.media.documents".Equals (uri.Authority);
        }

        private static bool EqualsIgnoreCase (this string first, string second)
        {
            return String.Equals (second, first, StringComparison.OrdinalIgnoreCase);
        }
    }
}