Summer is usually the worst time to buy an iPhone. This year, because of the global memory-chip shortage, it’s more complicated. In fact, some iPhones are safe bets right now. Apple unveils new phones and other hardware each fall. Usually, by holding off upgrades until then, you get a new device with a longer shelf life or, at the very least, the price drops on last year’s models. But analysts expect high-end iPhones will cost more this September, and the lower-priced models won’t be refreshed until 2027. Apple already raised prices on the MacBook Air, Pro and Neo, as well as iPad Air and…