Whether you are hanging shelves or putting together furniture, you may find yourself in need of a level. Conveniently, iOS 7 has included one, though it's not clearly apparent how to access it. The bubble (also known as spirit) level is not a stand alone app, rather it is accessed via the compass app:
1. Open up the compass app. You may be asked to calibrate the compass by rotating your phone a full 360°.
2. You will notice two dots at the bottom of the screen indicating that there is a second screen. Simply swipe left to get to the level.