Looking for a good on and offline mapping app for Iran

I plan on plotting archaeological sites to visit in Iran using uMap (https://umap.openstreetmap.fr). However, when I eventually visit Iran, I would need a program that can view the map data offline. I’m looking for a good iOS application (Apple iPhone and iPad) that will store offline maps where the sites are located. Most mapping programs are fine for the USA or Europe, but may not be as good for Iran. The app would need to be able to accept waypoints in GPS or KML, etc. Thanks in advance for your help.