I've finally found a decent music player on iOS, but it seems that arguably the most important function (for me, that is) is designed... not quite up to standards.

You can create playlists, but actually filling them with music is downright miserable if you've got more than ~100 files or so.

Right now it is
1. find some track
2. open it so it plays
3. add it to a playlist

Playlist with 200 tracks requires over 600 'clicks', not to mention that it takes at least a moment to open any file from the list. It is doable, but barely so.

What I would suggest is to make an 'add to playlist' button somewhere in the actual playlist view, which would show you a list of all the tracks you have, sorted by author, title or whatever and you could 'select' all the files that you want. It brings the total amount of 'clicks' to the number of tracks you actually want to add to a playlist and can be done at least few times quicker than the current way (not to mention that I'm still uncertain how to add a file to a different playlist than the one that is first on the playlist list).

Here's how I imagine it working: http://imgur.com/a/qfqgO

Thank you for your time