It's sometimes hard to keep up with what your options are to Photoshop on iPhone. Adobe used to have several separate photography apps including Photoshop Fix and Photoshop Mix. Those have now been dropped in favour of Photoshop Express, which has absorbed their functions.
Photoshop Express is a stripped-down, more social media-oriented version of Photoshop for mobile use. If you need more functionality on the move and you also have an iPad, there's now a fully fledged iPad version of Photoshop (See our Photoshop for iPad review).
There is also a Lightroom app for iPhone. This lets you apply presets, colour enhancements and selective editing on photos, and also allows you to edit videos on the go. For graphic design work, there is Adobe Express.