With Samsung launching its biggest attempt to challenge Apple’s reign in the smartphone market with Galaxy S3, rumors are piling up regarding what the Cupertino-based companies are up to in their next generation of iPhone.

Apple has not confirmed the release date of the next smartphone, dubbed iPhone 5 in the media, but people are expecting the device to come around September in conjunction or right after the release of iOS6 this fall which was introduced at WWDC 2012. And according to new rumor, it seems quite certain that the size has been increased to 4 inches.

The sixth generation of iPhone, according to rumors, will depart its 3.5-inch screen that Apple left unchanged until now. It may be a time for Apple to make a switch, since many Android-based phones are making bigger and bigger phones with screen sizes bigger than 4 inches.

Not only Apple rumored to add an extra 0.5 inch, but it will also change the ratio from 3:2 to 16:9, making it look more elongated. Several websites, such as 9to5Mac, have posted “leaked” photos of the new iPhone 5 designs.

This, however, would mean that the current iPhone developers may have to adjust their apps to fit the new resolution.

Fortunately, a feature called Auto Layout was made available in the development kit of iOS 6, which makes the transition easier. The features allow developers to set parameters for how UI elements appear on the screen, so the users can have a consistent experience across all devices.

Developers at WWDC were not too concerned about the change display, however. According to a poll conducted by Piper Jaffray’s Analyst Gene Munster, the difficulty on potential display image disparity was rated only 3.4 out of 10.

Is Apple going to release the new iPhone that has a 4.0-inch screen with 16:9 ratio this fall? Certainly, the introduction of Auto Layout supports the rumor of the display change.