Apple CEO Tim Cook says the firm will up its focus on China as it seeks to boost sales of its devices in a rapidly growing market. Speaking to the Xinhua news agency, Cook says he believes China will soon become the firm’s biggest market, ahead of current leader the US. To drive this growth, Apple is pouring huge investment into China, opening new retail stores and signing partnerships with local mobile operators, among others. Cook is understood to have met with China Mobile’s chairman while in the country. The operator is the largest mobile operator globally but currently does not offer the iPhone, which is only available on China Unicom.