There are very few apps for IOS that can run user-supplied and user-georeferenced maps, especially if you want to run aviation maps which are almost always with Lambert Conformal Conical projection.
Approach charts are easier because they use rectangular projection, but you would need to calibrate them yourself, which would take a lot of work.
Your best bet is to wait for Oziexplorer to come out under IOS, which should be soon. That will open up a route to running a vast range of maps and map projections, on an Ipad.