Access to locally stored files on my computer on my Iphone?

[Sigrid_74]

Hello, 

I have created a playlist on my laptop in Spotify that also contains files that are locally stored on my harddisk (and not available on Spitify). I can play this playlist from my computer and can find it on my Iphone. On my Iphone, hower, the playlist leaves out the local files and contains only the files that are available on Spotify. How can I play the local files from my Iphone too?

Thanks, Sigrid