Request Permission not working on Android Maui

Question

I am having an issue requesting storage read/write permissions. I have them Selected in the manifest file.

Onappearing I have:

PermissionStatus nWritePermission = await GP.CheckAndRequestStorageWritePermission();

The method is:

public async Task<PermissionStatus> CheckAndRequestStorageWritePermission()
{
    PermissionStatus status = await Permissions.CheckStatusAsync<Permissions.StorageWrite>();

    if (status == PermissionStatus.Granted)
        return status;

    if (status == PermissionStatus.Denied && DeviceInfo.Platform == DevicePlatform.iOS)
    {
        // Prompt the user to turn on in settings
        // On iOS once a permission has been denied it may not be requested again from the application
        return status;
    }

    if (Permissions.ShouldShowRationale<Permissions.StorageWrite>())
    {
        // Prompt the user with additional information as to why the permission is needed
    }

    status = await Permissions.RequestAsync<Permissions.StorageWrite>();

    return status;
}

The read is the same. The method is called, but I don't get the popup asking for the permission. I tried putting it on a timed loop to have it ask the permission again (running on ui thread) but it does not come up.

The strange part is that is was working, then I un-installed the app on the device and re-installed it and now it won't ask permissions.

When I look at the app properties in settings, it says no permissions are required by the app and none are given?

Answer 1

Hello,

============Update============

There must be a way to read a file from the Download folder. other apps like Adobe let you copy a pdf from your system to the device download and then open it.

If you want to use ContentResolver to read the binary file, you can use following code to read it.

#if ANDROID
        public byte[] ReadBinaryFile(string fileName)
        {
            ContentResolver contentResolver = Platform.CurrentActivity.ContentResolver;
 
            // query file
           Android.Net.Uri uri = MediaStore.Downloads.ExternalContentUri;
            string[] projection = { MediaStore.Downloads.InterfaceConsts.Id };
            string selection = MediaStore.Downloads.InterfaceConsts.DisplayName + "=?";
            string[] selectionArgs = { fileName };
 
            using (ICursor cursor = contentResolver.Query(uri, projection, selection, selectionArgs, null))
            {
                if (cursor != null && cursor.MoveToFirst())
                {
                    int idColumn = cursor.GetColumnIndex(MediaStore.Downloads.InterfaceConsts.Id);
                    long fileId = cursor.GetLong(idColumn);
 
                    System.Uri anotherSystemUri = new System.Uri(MediaStore.Downloads.ExternalContentUri.ToString());
                    Android.Net.Uri anotherAndroidUri = Android.Net.Uri.Parse(anotherSystemUri.ToString());
                    Android.Net.Uri fileUri = ContentUris.WithAppendedId(anotherAndroidUri, fileId);
 
                    using (Stream inputStream = contentResolver.OpenInputStream(fileUri))
                    {
                        if (inputStream != null)
                        {
                            using (MemoryStream memoryStream = new MemoryStream())
                            {
                                inputStream.CopyTo(memoryStream);
                                return memoryStream.ToArray(); // retrun  binary 
                            }
                        }
                    }
                }
            }
 
            return null; // cannot read the file
        }
#endif

Here is my code to write binary file to the download folder.

#if ANDROID

using Android.Content;

using Android.Provider;

#endif
 
        private void OnCounterClicked(object sender, EventArgs e)

        {

#if ANDROID

                        ContentValues contentValues = new ContentValues();

                        contentValues.Put(MediaStore.Downloads.InterfaceConsts.DisplayName, "my_binary_file.dat"); // file name

                        contentValues.Put(MediaStore.Downloads.InterfaceConsts.MimeType, "application/octet-stream"); // binary file MIME

                        contentValues.Put(MediaStore.IMediaColumns.RelativePath, "Download/MyApp"); // save path（Only works for Android 10+）
 
                        // get saved path url

                        ContentResolver contentResolver = Platform.CurrentActivity.ContentResolver;
 
 
                        // Convert System.Uri to Android.Net.Uri

                        System.Uri anotherSystemUri = new System.Uri(MediaStore.Downloads.ExternalContentUri.ToString());

                        Android.Net.Uri anotherAndroidUri = Android.Net.Uri.Parse(anotherSystemUri.ToString());

                        Android.Net.Uri uri = contentResolver.Insert(anotherAndroidUri, contentValues);
 
                        if (uri != null)

                        {

                            using (Stream outputStream = contentResolver.OpenOutputStream(uri))

                            {

                                if (outputStream != null)

                                {

                                    byte[] data = { 0x01, 0x02, 0x03, 0x04 }; // simple for binary file

                                    outputStream.Write(data, 0, data.Length);

                                }

                            }

                        }

#endif

        }
 

============================

Starting in Android 11, apps cannot create their own app-specific directory on external storage. To access the directory that the system provides for your app, call getExternalFilesDirs()., So you cannot request write external storage permission.

For Android 12 or later, application need to request and grand the MANAGE_EXTERNAL_STORAGE permission, then application could write files to the SD Card or external storage.

Declare the MANAGE_EXTERNAL_STORAGE permission in the manifes

this permission needs to open the android application settings page, then grand this permission by users.

You can use Conditional compilation for android platform code.

For example, you want to request this permission in the button click event. you can popup a SnackBar, tell user about this permission needed and let user to click.

private void OnCounterClicked(object sender, EventArgs e)
        {
#if ANDROID
            var activity=Platform.CurrentActivity;
            if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.R)
            {
                if (!Android.OS.Environment.IsExternalStorageManager)
                {
                    Google.Android.Material.Snackbar.Snackbar.Make(activity.FindViewById(Android.Resource.Id.Content), "Permission needed!", Google.Android.Material.Snackbar.Snackbar.LengthIndefinite)
                            .SetAction("Settings", new MyClickHandler()).Show();
                }
 
            }
#endif
        }

If you request this permission, you need to notice all-files-access-google-play document.

Best Regards,

Leon Lu

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.