I\'m building an app which would have to have the ability to show my own views on the iPhone lock screen. I\'ve seen lots of apps which let you customize the lockscreen and
It can be changed programmatically (change to SpringBoard), but it won't make the way to the (official) AppStore. So if you want to build an app that can change something like the lock screen wallpaper or the ring tone which you usually need the Settings app for, you have to publish your application via Cydia, not Apple's store.
For a sample code block, see this answer.