One of my favourite features of the Google Maps app is its ability to save offline maps on the iPhone. Whether you want map access regardless of cell reception or you’re travelling abroad and won’t have a data connection, Google Maps is king. While I enjoy Apple Maps’ built-in integration as much as the next person, there’s no denying there are certain times when Google Maps just can’t be beaten. For me, the two big ones are transit directions and offline maps. I frequently save offline maps on the iPhone with Google Maps when I’m travelling to a new area I’m unsure of. Even if I have a foreign SIM in another country, Google Maps allows you to get driving directions and to view maps in detail that you’ve saved offline.
How to save offline maps on the iPhone with the Google Maps app.
 Launch the Google Maps app and search for the area you want to save.
 Tap on the menu button and choose Offline areas.
 Tap on the plus button in the lower right corner.
 Pinch and zoom the area to fine tune what you’d like to save
 Tap on Download.
 In the popup menu, give your area a unique name and tap Save.