Apple customers in selected mainland Chinese cities can now get a new iPhone delivered to their door for free within three hours, as the US tech giant steps up efforts to defend its turf in the world’s largest smartphone market.From Wednesday, three-hour delivery is free for in-stock items including the iPhone, iPad, Apple Watch, MacBook Pro, MacBook Air and AirPods. Other products will incur a delivery fee of 45 yuan (US$6.40).Apple normally charges 45 yuan for its express service in mainland...