Yes, there is!
Just like Android application, there is an iOS application to add 'Shot On' and 'Shot By' tags to the photos captured using iPhone named 'iShotOn Watermark Stamper'.
Along with the ShotOn tags you can also include the 'Brand Logo' of your device!
you just have to follow few steps and that's it. Capture picture and a stamp will be added t it!
Hope you will like it!