Apple is widely rumored to release the iPhone 6 in 4.7-inch and 5.5-inch models, with the 4.7-inch model sporting a resolution of 1334×750 pixels at 326 pixels per inch. So how will Apple change iOS to adapt to this new resolution?

The company has till now released just two different sizes of the iPhone — the first five generations had a 3.5-inch screen, while devices after that had a 4-inch screen. The first transition was from the 320 x 480 display of the iPhone 3GS to the 640 x 960 Retina display on the iPhone 4. With the iPhone 5, Apple for the first time altered the physical size of the iPhone from the earlier 3.5 inches to 4-inches, at a resolution of 640 x 1136 pixels.

A 1334×750 pixels display at 326 ppi means that icons, text etc. would be the same size as the iPhone 5s, but there’d be a lot more room left for including more area of a list, web page or icons. Here’s a mock up of the iOS home screen on a 4.7 inch screen:

As you see, the larger screen will let Apple add another horizontal row of icons on the home screen, and give them a lot more breathing room.

Through all these transitions, Apple ensured that developers didn’t have to do a lot of work to update their apps for newer sizes and resolutions. So how would developers add compatibility for the larger 4.7 inch screen?

Apple’s engineers have been preparing for such a change in display size since quite sometime. They introduced a layout engine called AutoLayout in iOS 6 to let developers make interfaces for different screen sizes, and this is probably what developers will have to use to add support for the larger screen.

Until then, iOS could automatically letterbox unoptimised apps, as shown in this Verge forum post:

Such a theory falls in line with Apple’s strategy in the past, where the 3.5-inch apps ran letterbox-ed on the iPhone 5, iPhone apps ran in scaled mode on the iPad and so on.

Let me know what you think in the comments. Are you looking forward to iPhone 6 with a bigger screen?