dont compare gramin with google maps.. I tried caching and navigating and it gave me network error.
Have you tried it?
Offline navigation does work but there are a few gotchas that you have to be aware of.
Firstly you have to ensure that you search for your destination and cache the map (using ok maps as indicated) whilst you have internet connectivity.
Then you should ensure that you leave the maps app on the screen where you are about to hit the start navigation button with the suggested route visible. You can return to your home screen though and when you are about to start your journey and assuming you no longer have internet connectivity you can reload the maps app. As long as you are then taken back to where you can hit the start navigation button it will work. But if you try to search for your destination again, even though the map is cached, you have to have internet connectivity to do so.
Other things to be aware of is that although the whole map area is cached, only the route suggested initially is cached. So if you go off route you will be left without verbal and visual directions. You will just see the arrow on the map moving along the map. If you manage to rejoin the suggested route then it suddenly comes back to life. If you only go a bit off route then it sometimes gives you visual directions and if verbal directions continue then you will notice that you will lose street names and will simply get "turn left, turn right" etc. If you go further off route then it stops as mentioned previously.
I know all this because I've done it several times just to see what it could and couldn't do when offline.
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