We have a photo sharing native app in Objective C and Java. Backend code is in PHP, what's the best way to get high resolution images on the app with fairly low file size so it doesn't slow down the response time?
You might want to play around with an image handling library like Intervention Image[1]. I recall a presentation by instagram on how they made their image sharing fast, might be worth looking into that (as well as hooking up Charles Proxy to their requests to see what sort of stuff they are sending over the network).