Did not help me
Although some of the reviews give high marks to this app, it didnt work for me. Unlike a true stud finder, it can only sense nails and not the stud itself. For some reason it found very few nails for me.
Maybe its better used for really finding metal and use as stud finder is secondary.
RonHoef about
Free Metal Detector - Stud Finder and EMF Meter in One!