So often you need to show a UIImage which allows zooming & panning. You could either use a fullblown imageview controller (which takes over all ownership of the image viewing), or write it yourself within your viewcontroller.
I stumbled upon this issue multiple times. I wanted to show a UIImage somewhere on screen and add support for zooming and panning. Each time I was messing around with a UIScrollView in combination with a UIImageView and every time it was a lot of work in order to get all features implemented people were expecting (double-tap, single-tap, ...). I looked at both EGOPhotoViewer and MWPhotoBrowser but since they both force to use their UIViewController too, it wasn't a viable solution (they add a toolbar, navigationbar, ...)
I now created a public Github library, NWImageViewer (based upon work from Michael Waterfall (MWPhotoBrowser)) which exactly does this. Provide you with a single UIView which you can set a UIImage on, and the view supports zooming and panning. It informs you when important things happen through a delegate.
Go check it out and let me know what you think!