It's time to upgrade! The latest version of the iPhone has hit store shelves.

Anxious Apple fanatics lined up early to get their hands on either the iPhone 6 or the iPhone 6 Plus, with some even waiting in line overnight. Workers at the AT&T store at the Bay Plaza Mall handed out free snacks to those standing in line to make the wait more pleasant.

The iPhone 6 has a 4.7-inch display, while the Plus version is a full 1.5 inches bigger with a 5.5-inch screen. The new model is being dubbed as Apple's biggest system makeover ever.

Both feature a faster A8 processor, an improved camera with optical image stabilization and a way to measure exercise activities that can be integrated with the new Apple watch.

Apple says it sold a record 4 million smartphones last Friday, the first day the iPhones were available for preorder.