Piper Jaffray says buy Apple shares because its 'wider array' of new iPhones will spur demand

Piper Jaffray is optimistic over Apple's upcoming lineup of iPhones.

The firm reiterated its overweight rating for Apple shares, predicting the smartphone maker will sell more iPhones in its next fiscal year than the Street currently expects.

Apple is widely-expected to announce new iPhones of varying sizes on Sept. 12.

A broader spectrum of choices for the next generation of iPhones "will drive unit upside," analyst Michael Olson said in a note to clients Friday. "With the potential launch of a wider array of 'X-gen' iPhones imminent … we recommend owning Apple for the 'super-long' cycle involving an ongoing multi-year move" to the X generation phones.