Apple spending not really "IT spending"
It would more properly be categorized CE spending, since Apple gets the bulk of its revenue from consumer sales. The quarterly drop for Apple is easily explained Chinese New Year falling in the previous quarter rather than this quarter - an important date for consumer sales, but not for enterprise spending (probably would actually hurt enterprise spending in that quarter, as many people take the week off)
Though obviously if the economy in China really takes a tumble and people quit getting 30% raises every year and feeling rich, the spending on iPhones will take a serious hit.