Question

Does anyone know what will happen with existing apps when they run on the iPhone 4.0 in terms of the new screen resolution? I am assuming, just like developing for the iPad that there should be no hard coded screen resolutions in your code.

I’d also like advice on the best way of writing robust code to work well on any device. For instance, detecting the screen resolution is not enough – on the iPad the screen is physically bigger so you can display more items on it. On the new iPhone the screen is the same physical size but higher resolution, so the likely thing is that you wont want to display more items, just higher resolution versions of them.

Any help would be useful,

Regards

Dave

EDIT: I have read the other similar posts, I guess what I really would like to know is what is the recommended way to write code for all App Store devices in a robust way so they a) all work b) make best use of the device.

Answer 1

UIKit has be redesigned so that old apps just work unmodified in the iPhone 4. There are then several things you can do, some programmatic and some by just adding higher resolution images to you app bundle.

Firstly, and most simply you can include new double res images that are used by your app with a suffix of @2x in the name. i.e., Event.png as well as [e-mail]. [UIImage ImageNamed:] will automatically look for the a file with this suffix if it is running at the higher res.

All the other UIKit stuff now uses points instead of pixels. So for both old and new apps full screen is still 320 x 480 points. This pretty much means everything will work including touches, etc. Although they may now return fractions of a point.

The only real gotcha so far seems to be if you use CGBitmapContextCreate as this uses pixels and requires some jiggery – pokery.