peck with his take on all things twitter. but we start with the biggest nim in tech -- name in tech, the most earnings report this season. it is of course apple. josh lipton just sitting down with the ceo tim cook moments ago. josh, what is the latest? >> reporter: well, simon, listen, the big question for apple investors is whether that company can grow iphone units next quarter but in to 16. skeptics will point out, listen, there are real challenges, maturing smartphone market, a slowing china and tougher comps and i did speak to ceo tim cook. he is confident they can gain those units. one, they continue to see the highest race of switchers from android. it is a point cooke made over the past few quarters. i was interested whether that had leveled off and cook said no, that switch rate continues to be very high. he said, listen, about 70% of the install base are on a 5 s or older and that would suggest the potential for upgrade head room ahead. and as for china. we know some worry about the slowing economy, what would that mean for apple's business. tim cook told jim cramer, remember, that china's business there was strong in july and august. coo