Loading UIImages automatically in high-resolution works fine for locally stored images – but if you want to fetch them via remote URL you have to code yourself.
A simple, blocking but backward compatible (iOS >= 3.0, maybe even 2.0 but untested) implementation could look like this:
@implementation UIImage (MRORemote)
// add the @2x filename suffix
+(NSURL *)url2x:(NSURL …
A quick comparison how fast images load on the iPhone using a simple UIImage imageWithContentsOfFile:. Each image is 8-Bit RGB without Alpha:
Filename
Bytes
msec
img-10000×50.png
224193
283
img-50×10000.png
200397
643
img-900×600.png
879483
623
img-30000×100.png
727709
1222
img-150×20000.png
911923
2218
Looks like the horizontal strip is the winner when it comes to loading speed.