It appears that the clock timer app in the latest version of iOS is finally working. So if you're wondering how you can add that sleep timer functionality on your Spotify or Apple Music on your iPhone or iPad, then, watch the video below and see how it's done:
This trick also works on other music player or podcast apps like Pandora, Rdio, etc. It basically kills whatever media playback active on your iPhone or iPad once the timer's up.
