title: Get device image scale (e.g. @1x, @2x and @3x)
body: <p>I have an app that uses a service to get some icons. </p>
  
  <p>With this service I can get any image of any size, so I've planned to get the 3 images (@1x, @2x and @3x) and store them on the BBDD, and then get the scale to use one of these three; or maybe get only the one according with the device scale.</p>
  
  <p>But the thing is, how can I get the device scale (@1x, @2x and @3x) programmatically? </p>
  
  <p>Both Obj-c and Swift are welcomed ;)</p>