Of the many features unveiled in iOS 6, one wasn't how the new mobile OS will work on the iPhone 5. That's probably because Apple will have a dedicated event for the device, though more evidence suggests the smartphone will launch with a bigger screen.

That evidence is called "Auto Layout," a feature that basically allows UI elements to be easily positioned across form factors. Auto Layout sets defined rules on where buttons should be relative to the rest of the UI, for example, suggesting Apple could be at least increasing the screen size of the phone and may refresh the UI.

Auto Layout would allow there to be a quicker turnaround for developers if the iPhone launches with a 4-inch screen, especially if the look of the OS is revised. Apple has used the grid-based layout on a 3.5-inch screen since the iPhone debuted in 2007, and that has caused some users to label the OS as "boring" and demand a refresh.

It's a contrast to Android: icons can be moved around freely, and skins such as MIUI change the look of the operating system completely.

Auto Layout also means that developers will be able to approach new markets, such as China, easily and localize apps. Nokia's decline in the market means there's an opening for competitors to fill, and supporting China could be Apple's first steps towards the market.

Of course, Apple could just maintain the 3.5-inch form factor. Auto Layout didn't debut in iOS 6, but then there's the question of why Apple highlighted the feature when it's been around since OS X Lion.

One developer described no inclusion of Auto Layout in a 4-inch iPhone as "crazy." Considering Apple's turnaround from new product announcement to launch is relatively quick - the iPhone 4S was announced October 4, 2011 and the first delivery date was October 14, 2011 - having an App Store supporting a new screen size from launch is essential. A problem among Android apps is that it's hard to develop a consistent experience across apps, because of the wealth of different screen sizes and installed versions of Android.

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