Just in case you weren’t convinced of an imminent 4-inch iPhone from all the rumors and speculation flying around the Internet, 9to5Mac dug into iOS 6 to all but confirm that the next-generation iPhone will in fact have a larger 640×1136 resolution display. For the first time, the UI elements within the OS are scalable.
iOS 6 is the first release of iOS that is scalable for a bigger display, or at least one with more pixels. 9to5Mac made some tweaks to the iOS Simulator so it could run at the rumored 640×1136 resolution display and sure enough, iOS 6 takes full advantage of the extra space. The home screen fits five rows of apps on a single page compared to the previous four, not including the dock. The icons are spaced out perfectly.
In fact, iOS 6 will not display the five rows of icons correctly at any other resolution than 640×1136, so that seems like the winning pixel count.
What happened when iOS 5.1 is loaded onto the tweaked 640×1136 iOS Simulator? The home screen isn’t optimized. The same four rows of icons are present as with current 3.5-inch iPhone models and they’re stretched out across the screen so that each row has a gap between it.
At the very least, Apple is only testing a 4-inch display somewhere within those Cupertino headquarters, but at this point I think we can just leap right across the skepticism and conclude that the next iPhone’s display will almost certainly measure to 4 inches — 3.999 inches if you want to get technical with it.