Ask HN: Could any iOS Developer Give me some pointers? | Hacker News Reader

Ask HN: Could any iOS Developer Give me some pointers?

I'm quite new to iOS Development and wanna get stuck right in :) I'm just looking to find the best practice for this:

I know I can use CLLocationManager to get the users location but I want to create an app that does this:

User logs in > app checks web server for online users in specified radius in miles/feet of the current users phone > displays users.

What is the best way to go around this? much appreciated for all your help.

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I think stackoverflow is better for this specific question.

Having said that most databases (on the backend) have spatial extension where you can run queries like 'where inside(point,geometry)'. So you create a bounding box or circle around the user, then run a query. That's faster than calculating distances between all users. The databases have special indices for geographic lookup. Both point and geometry probably need to be specified in WKT format. http://www.gaia-gis.it/spatialite-2.1/SpatiaLite-manual.html http://docs.mongodb.org/manual/applications/geospatial-index...

Assuming you have the coordinates for the each online user, iterate that collection, create a CLLocation object from the coordinate data, and check that object against CLLocation method distanceFromLocation with a radius value.

https://developer.apple.com/library/ios/documentation/CoreLo...:

Also as @mtmail mentions, the better path for this is probably not on the device itself. It would get expensive where N number of users is really high. Perhaps at the service layer, send the device location to the service, and have the service return the nearby users.

Yes. When the user opens the app I will get their current location and add it to a column in the database 'currentLocation' Then I will query the database like so: select * from users where userOnlineStatus = 'online' and currentLocation = ""; <- That is what I would want to do. Its just calculating the distance so that not all random users are showing up.

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