try Gaiagps- it's $20, but $ well spent- you download 24k:1 topo maps (or different sizes or even satellite maps) for whatever area you want, simply name them and save them
before heading out, load the map you need- turn the phone to airplane mode- this prevents the battery from getting eaten up, but the gps still works; I've had my iphone 6 last 4 days w/ battery life left- that using the map app daily and taking lots of photos
tracking will eat battery life quicker; I only use tracking for very short term or on day outings
I've ditched both my camera and gps in favor of the iphone- do invest in a good weatherproof case for it though
