I just use Stash2Go to upload pics to my projects on raw and sometimes to browse patterns when I'm bored and not near a computer.
I also use Adobe PDF Reader on both my computer and iPhone, synched across the adobe cloud, to manage my patterns. This way when I mark off lines I've completed, it's updated across both devices. It's basically like printing a pattern and crossing off with a pen, except I can't lose the paper b/c it's in the cloud.
I also have a row counting app called "Row Counter." It's simplistic in that it can only count rows for a single project at a time, but I love it b/c it has an Apple Watch component so I can mark rows completed without having to pull out my phone -- handy so I don't have to set my needles down after each row! Then lastly I also have an app called "Knit Counter" where I keep track of my row counts per-project b/c the other one only does one project at a time.
I apparently have knitCompanion installed but I have never used it and I'm not sure when/why I would... I'm sure it was recommended to me at some point.