Having signed a long-awaited deal with China Mobile, Apple now has greater access to 763 million Chinese consumers. The agreement was announced on Sunday and the iPhone will launch with China Mobile — the biggest network carrier in the world — on Jan. 17. But Apple still faces some big hurdles to rapid growth there. In China, the iPhone can cost more than eight times as much as Android-operated smartphones. As a result, Apple ranks just fifth in the national smartphone market.