GPX file navigation on iPhone

Hey dudes - a question by the way of my boss who is riding the Munda Biddi Trail in 30 days. He has gained access to the GPX file and wants to have it as a back up for navigating the route each day. Has anyone used anything on the iPhone that will give you the directions as you ride, or alert you if you veer off the path?

MapMyRide?

I was going to recommend the one I used but it’s only on Android.

https://www.google.com.au/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=gpx+ios

Heard good things about Gaia but costs moneez. MapMyRide is good but needs connection. Paid version does offline.

He doesn’t need it

Just follow the maps and have a good time

Related but not necessarily iPhone.

I quite like Avenza maps app - on android, they appear to have apple version as well.
http://www.avenza.com/pdf-maps

I can download maps from the Avenza store - for example Vic Parks has free maps for most of their parks available for download on the avenza store.
https://www.avenzamaps.com/maps/search.html
These maps are pdfs but they have embedded gps info, so the mobile app shows your position when you are on the maps.

I can make gpx files on mapmyride or something similar and export them OK to a device that accepts gpx files.

But I’d really like to find some way to combine the gpx files with a topo map and make a pdf with geo info that can be imported into the avenza app (or similar). There is mapping software that costs $100+. But I am looking for a free option - any suggestions?