Spotify is one of the most popular cross-platform streaming music services, with over 40 million active users worldwide. While I am out of luck using the service as a Canadian, our neighbors to the south and elsewhere can benefit from a jailbreak tweak called DefaultSpot. The simple iOS extension sets Spotify as the default music player on iPhone, and also integrates with the Control Center playback controls.
DefaultSpot makes Spotify the default music player on iPhone