Apple iPhone 6 event officially set for Sept. 9?

Apple on Thursday sent out invites for a press event on Sept. 9 in its hometown of Cupertino, Calif.

The company provided few hints about what will be announced beyond saying "Wish we could say more." That could indicate something related to Siri, Apple's digital voice assistant. Generally, Apple is expected to introduce its newest iPhone, dubbed the iPhone 6.

The event will come a year after Apple introduced the iPhone 5S and 5C and a week after arch rival Samsung is set to unveil its Galaxy Note 4 phone-tablet hybrid, or phablet. Apple has added a new iPhone every year since former CEO Steve Jobs introduced the smartphone line in 2007, and new iPhones have been unveiled in the fall since 2011.

Many market watchers expect Apple to introduce two new iPhone 6 models with display sizes of 4.7 and 5.5 inches, though some recent reports speculate one device could be released at a later date. Analysts expect the iPhone 6 to be one of the largest product launches in Apple's history -- both in terms of device screen size and total sales. The company reportedly has asked manufacturing partners to produce about 30 percent to 40 percent more iPhones by the end of this year than it ordered for its initial run of last year's iPhone 5S and 5C.

For Apple, having a successful iPhone 6 launch is vital. Apple hosts only one phone event a year, and it generates more than half its revenue from its smartphone line. The iPhone serves as the lynchpin to Apple's overall growth, particularly as the market awaits the widely speculated iWatch and as the iPad struggles against lower-cost rivals and larger phones.

Apple also could show off a wearable at the event.