Thank you for liking it. Face recognition involves more models, and about geolocation information, you can actually get latitude and longitude from photos, but converting them to specific cities and neighborhoods requires access to geolocation servers, which will cause the app to have to be networked, which is not what I would like to see.

For Geo-Location, maybe consider this workflow: User searches City in the iPhone Maps App (by Apple), then clicks "Share" button, then "Copy to Clipboard" - thenpaste this location into your app, you grab Longitude & Latitude from that and let users specify a radius. Bam! Complicated.... But no network needed.

Someone else has commented with a list of cities which could be included offline: https://news.ycombinator.com/item?id=34690693

But your workflow is such a hassle that I doubt many people would do it. A more realistic flow (without the list of places above) would be to show an image of the world map, allow the user to zoom in, and let them drop a pin on the map. They can drop a pin near some pixels labeled Paris, but the app doesn't need to know that it's Paris, it just needs to translate the pixel coordinates of the pin (relative to the image) to geographical coordinates, and look for images close to these coordinates.

Potentially the app could link out to a hosted webpage that allows selecting a location using a decent map and search UI, with network capability (but without requiring it in app)

Then on selecting a location you present a button that then jumps you back into the app via a universal link (passing in lon/lat)

Is it a possibility to have some sort of offline database to query against ? Or maybe that would make the app to heavy. Could be a "opt-in" download.

Maybe an offline mapping table + a bit of similarity algorithm can roughly solve this problem, just not too precise for cities.

Why not? How many cities do you think there are?

Including a dump of just lat/lon/rad->city from openstreetmap probably kilobytes. Including towns and features might be low megabytes.

Maybe you're right, I'll try.

Mapbox added offline map support a few years back on their SDKs, Found a couple medium articles on it, but no code to share. Wondering if there might be any mapbox FOSS replacements that offer this?

My current idea is probably: store the latitude and longitude of major cities in the world in a txt file, load it, and then estimate the distance based on the difference between them and the current photo, not sure about the space taken and the time consumed.

If I was you, I would not try to add the geolocation, you won’t match google anyway and it will take you way too much time.

But up to you