I would be a little suprised if the UK ones worked since currently Memory Map has a commercial monopoly
on these by the CAA, and from 2010 onwards they are encrypted so cannot be imported into some other format.
The only way to run them is to scan the paper maps but there is no way to do that legally.
Maybe MM will license them out but I have not seen this happening widely so presumably they want too much for it.
All that a 3rd party app like this could do to facilitate running the UK charts is to run a TIFF or similar graphic file, with a separate (or embedded e.g. GeoTIFF) georeferencing data, but the user would then be stuck with getting the map scanned by a bureau with an A0 scanner, which probably costs a packet.
The best solution is Oziexplorer (whose mapping community has loads of scanned aviation charts) but I don't think they have an Iphone app out yet. They are talking about it.