A turning point that needs to be understood. Yes, this geographic internet service developed by Google, which allows searching and viewing maps of a large part of the world, accessible via a website or mobile app, can also be used offline. And it’s the same even if you have Apple, then iOS, then Maps.
The service that revolutionized the world of travel (short or long doesn’t matter) was launched back in 2005, first available for Internet Explorer and Mozilla Firefox browsers, then a few weeks later, on February 25th, support for Opera and Added Safari. 
Google Maps – Cellulari.it
Google Maps based on a variant of the projection of mercator uses the formulas of the spherical projection of mercator even if the coordinates are based on data from the geodetic world system WGS84. The difference between a sphere and a WGS84 ellipsoid is the cause of inaccurate projection, which is particularly noticeable in large-area displays.
Don’t panic, there is a solution for everything
All this goodness is usable from a practical point of view by GEOGRAPHIC POSITIONING SYSTEM, or better yet, when we’re online. Problems could arise when we are in areas where there is no field. Don’t worry, don’t panic.
There’s a trick of sorts to the Google Maps experience (but also from cards with i melafonini), even without a connection. Everything starts with a premise. 
Google Maps – Cellulari.it
You must have offline maps on your smartphone to view them. A kind of joker that you can pull out in an emergency. You need the connection… Wireless Internet access: Select an external storage medium in the settings menu in order not to fill up the internal memory.
Offline Maps is in the menu that appears when you click or “Tap-Pato” on the three segments at the top left or by scrolling from the left edge towards the middle. “offline maps“Shows the automatically downloaded map sections of your favorite places. And that’s it, it will always be important to select the download area so that you can find it again if necessary.
It’s more or less the same on iOS devices: side menu, offline maps, then “Custom Map” to select the area to download.
One last recommendation to remember. The use of offline maps excludes all the “plus points” associated with the connection: traffic information, for example alternative routes, directions for arriving on foot or by public transport. It’s the price of having maps available when not connected.