This android app was mentioned in
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You download each city you want. I got off at the wrong station in Berlin without knowing, walked outside and to the closest intersection, and found the street names. I search those in that app, figured where I was, and which direction I needed to walk. I was at my hostel 20 minutes later. I have several other stories like that. An offline map was a life saver!
I just found out about CityMaps2go from another reddit thread. Seems promising. There's also the TripAdvisor apps. Unfortunately, I don't use either so I can't give any sort of review of them.
Make sure your language apps use traditional Chinese, else you'll be learning the wrong set of characters. The Google Translate app can be used offline as can the Pleco Chinese dictionary. I totally recommend these.
Write out what you want translated in Pleco as it doesn't give a time limit in writing characters so you can try to figure them out before it auto-guesses for you, and then copy-paste to Google translate. Google translate isn't perfect but it's close enough.
On mobile so I apologize for any formatting errors.
City Maps 2Go. Be sure to download the maps on WiFi before going offline. I used this app to map all the key sightseeing points before going out. Very handy.
CityMaps 2Go Android iOS
Shows little paths that a lot of other maps don't, helped me quite a bit on holidays while exploring and didn't really know the area that well.