Why Are iPhone Sales Sluggish?

On Tuesday, Apple shares fell more than 4% Tuesday.
Business Insider reports there is growing concerns around a slowing iPhone cycle.
At least four of the tech giant's suppliers have cut their own guidance due in part to weakness in the smartphone market.
What is causing the slowdown in the iPhone market?
Angelo Zino, senior equity analyst at CFRA, says the slowdown is due largely to rising prices.