I’ve installed my iPhone app on an iPad. When I tap this “2x” button, the app gets scaled up, but it doesn’t use my retina display graphics. Isn’t that somewhat stupid? I am sure I did something wrong!
What must I set in the info.plist or elsewhere that the iPad will use my retina display graphics when the app is watched in 2x mode?
No, it literally just scales up the screen. It may be a bit lame but that’s by design. Note that even the text is pixel-doubled.
If you want to make better use of the screen you have to make a “Universal” app.