I am using an iMac to do OS X App Development, but my iMac is not a retina display. Is this possible to let me simulate the result on retina display Mac? Thanks.
I used Quartz Debug to get a HiDPI entry in Displays. This was pre-Mavericks, so I'm not sure if that's still the recommended way to do it.
The answers here mention a couple different ways.
You may also need to hold Option while clicking on "Scaled" in Displays.