What is the best way to get spoken turn-by-turn driving guidance from a .GPX coordinate log file on iOS?

I went on my first club driving tour in July, and had a lot of fun, but had a lot of trouble actually following the route. I drive alone, and quickly realized that a) to follow printed directions I must read them, which is a problem while driving, and b) the .GPX reader I tried on my iPhone had much the same problem, requiring me to look at the screen to know when I had just missed a turn but not telling me when a turn was ahead.

So far the only suggestion I've gotten has been RideWithGPS which does indeed look promising, but the features I want seem to require a paid subscription. Is there a better alternative?

I understand this is a tough programming challenge. I have no problems pre-processing the .GPX file offline and loading the result to my phone if that works better.