Check if user added new music on Windows Phone 8.1

Question

I’m trying to find out if the user has added new music to the “Music” folder on the phone since the last application was used.

I try to do this by setting the DateModified folder from Music (which correctly updates on the computer when adding new music to the phone):

async void GetModifiedDate ()
{
    BasicProperties props = await KnownFolders.MusicLibrary.GetBasicPropertiesAsync();
    Debug.WriteLine("DATEMODIFIED: " + props.DateModified.ToString());
}

Unfortunately, this returns:

DATEMODIFIED: 1/1/1601 1:00:00 AM +01:00

Am I doing something wrong or is there another quick way to check if the user has added new music?

Answer 1

KnownFolders.MusicLibrary - , , , .

, DateModified , . . ( ). - , DateModified .

, , , MusicLibrary, , . , , . , , ( ). , Tuple<file.FolderRelativeId, fileSize> ( ecample).

FileQueries Windows Phone, , :

// first - a method to retrieve files from folder recursively 
private async Task RetriveFilesInFolder(List<StorageFile> list, StorageFolder parent)
{
    foreach (var item in await parent.GetFilesAsync()) list.Add(item);
    foreach (var item in await parent.GetFoldersAsync()) await RetriveFilesInFolder(list, item);
}

private async Task<List<StorageFile>> GetFilesInMusic()
{
    StorageFolder folder = KnownFolders.MusicLibrary;
    List<StorageFile> listOfFiles = new List<StorageFile>();
    await RetriveFilesInFolder(listOfFiles, folder);
    return listOfFiles;
}

, , , .

Answer 2

:

ulong musicFolderSize = (ulong)ApplicationData.Current.LocalSettings.Values["musicFolderSize"];

BasicProperties props = await KnownFolders.MusicLibrary.GetBasicPropertiesAsync();
if (props.Size != musicFolderSize)
{
    //  ...
    ApplicationData.Current.LocalSettings.Values["musicFolderSize"] = props.Size;
}

Answer 3

Romansz:

, , - , , .

- KnownFolders.MusicLibrary.GetFilesAsync(CommonFileQuery.OrderByName);, . , . ,

        //cache the virtual storage folder for the loop
        StorageFolder musicLibrary = KnownFolders.MusicLibrary; 
        uint stepSize= 50;
        uint startIndex = 0;
        while (true)
        {
            IReadOnlyList<StorageFile> files = await musicLibrary.GetFilesAsync(CommonFileQuery.OrderByName,startIndex,stepSize);

            foreach (var file in files)
            {
                //compare to see if file is in your list
            }
            if (files.Count < stepSize) break; 
            startIndex += stepSize;
        }