Apple cut its revenue outlook for the latest quarter Wednesday, citing steeper-than-expected "economic deceleration" in China and emerging markets.The rare revenue warnings from Apple suggested weaker-than-anticipated sales of iPhones and other gadgetry, in part because of trade frictions between Washington and Beijing.Apple shares slid some 7.6 percent in after-hours trade on the news.The company slashed its revenue guidance for the first fiscal quarter of 2019, ended 29 December,