Look into Motion X GPS app for iPhone. Costs $1.99 at App Store and there is no subscription required. You can download maps for use when there is no cell service. It will allow you to use tracks like a portable GPS. The offline maps you download can take a lot of space if the area is large and you want maximum detail. Even if the map doesn't have a lot of detail for your area, if you start a new track when you start your hike you should be able to find your way back and retrace your steps. I bought this to replace my handheld GPS when it died. Hope this helps.
