Slumber is a new Cydia tweak that's probably the right answer to a few Reddit threads asking about the Stop Playing music function of iOS 7's Clock Timer.
Within the stock Clock app in iOS, you have the Timer. Basically used for countdowns, Timer also has one function within “When Timer Ends” that a few people use: the Stop Playing. What this feature does is it stops the music app after the countdown to a preset time is over. The most prominent application of this feature is when you hit the sack, need to listen to some music but want to make sure the music stops even if you fall asleep without stopping it yourself.
As with all glorious iOS features, Apple decided that this feature should be exclusive to the stock Music app only. So if you were streaming music from Spotify or Pandora or any other music app like Picky, the Stop Playing feature wasn't going to be helpful. If you fell asleep without turning off the music from these apps, they're going to keep playing and drain your iPhone's battery throughout the night.
The solution comes in the form of a very simple Cydia tweak. It's called, very aptly, Slumber.
Slumber doesn't have anything to configure. There's an Enable/Disable toggle (the kill switch, if you will). Once enabled, you can head over to Clock → Timer → select a time and then for When Timer Ends, choose Stop Playing.
Previously, Stop Playing would only affect the stock Music app but with Slumber enabled, it will affect any music app that plays music on your iPhone. This includes the popular Spotify or Pandora and any other app that you use to play music.
While it's not know how many people actively use third-party apps for music on the iPhone, Slumber is definitely a must-have if you do use other apps for music.
Slumber's kill switch can be accessed from Settings → Slumber.
The interesting thing, however, is that third-party music apps are being developed with a built-in switch for sleep timer. Pandora, for instance. (and given the number of requests for this feature on Spotify's user forum, I guess the next update might bring the feature to the table).
Slumber's up on the BigBoss repo and it's available for free.