Apple is understood to be developing new iPhone designs including bigger screens with curved glass and enhanced sensors that can detect different levels of pressure.

Two models planned for release in the second half of next year may feature larger displays with glass that curves downward at the edges. Sensors that can distinguish heavy or light touches on the screen may be incorporated into subsequent models. With screens of 4.7 inches and 5.5 inches, the two new models would be Apple's largest iPhones, and would approach in size the 5.7-inch Galaxy Note 3 that Samsung Electronics debuted in September.

The South Korean maker last month released its curved-screen Galaxy Round, the latest phone in an array of sizes and price points that’s helping keep Samsung ahead of Apple in global market share. The new Apple handsets are still in development and plans haven’t been completed, although the company may release them in the third quarter of next year. Natalie Kerris, a spokeswoman for Cupertino, California- based Apple, declined to comment.

“Screen size is one of the things where Apple has to catch up to the Android camp,” Dennis Chan, an analyst at Yuanta Financial in Taipei, said, referring to phones using Google’s operating software. “Innovation in components has been a key for Apple since the first iPhone came out.”

Apple broke with past practice in September when it unveiled two versions of the iPhone at the same time, the iPhone 5s with more advanced features and the iPhone 5c at lower prices, as part of a strategy to appeal to broader markets. Demand for the iPhone 5s is much higher, and iPhone 5c production has been reduced, the person said.

Revenue growth for the current quarter, Apple’s traditional holiday sales period, may be the slowest since 2008, according to data compiled by Bloomberg based on the company’s financial forecast published last month. Samsung said last month it expects this quarter’s shipment growth rate from the prior quarter to fall to a “low single digit” percentage from the “mid-10 percent range” the prior period.

Bloomberg