tried almost every gps there is for the iphones, best was gaia i found also
you can pre load any maps you want to the cell also
leave the location service off while your out there, just turn it on when you want to check it and drop a flag,. saves the battery alot, theirs good small chargers out to for them. can get 3 to 5 charges for about 50 buck battery pack.
I use Gaia app on my smart phone, with maps pre-downloaded for area i'll be in. For long trips i use a simple bushnell back track gps, cave man simple but works every time.
I don't know about Gaia, but I installed HuntBuddy BC on my Android and then when i switched over to my iPhone it came along too which was a nice surprise. I think it should work the same for Gaia - as long as you bought it on one, your ID should be the same and it should come along to the second phone.
looks like you can have it on as many as you want.just plug usb into pc or laptop, and log in with the 1 acct that purchased the gaia
https://help.gaiagps.com/hc/en-us/ar...itional-Device