The report is the first to put a firm number on the scale of a recent decline in Apple's fortunes in the world's second largest economy, after Chief Executive Officer Tim Cook pointed to China as a big factor in a rare cut in the company's quarterly sales forecast last month.
Dissipating Chinese demand compounds the problems at Apple, which is struggling to deliver on another hit device as its marquee gadget loses some of its cachet.
Cupertino, California-based Apple's latest iPhone models, which are mostly priced above US$1,000, face a tough challenge from Chinese-brand devices that cost about half or a third less. To compensate for the loss, Apple is trying to replace phone sales with revenue from services.
Chief Executive Officer Tim Cook has seen China as a key part of Apple's strategy: last fiscal year the company generated nearly $52 billion in revenue from Greater China, a region that includes Hong Kong.
The figures in the report showed a 19.9 percent fall in Apple's smartphone shipments in the final quarter of 2018, while Huawei's grew 23.3 percent. The Chinese slowdown was also the driving factor behind Apple's first revenue outlook cut in nearly two decades.
"When smartphones became a commodity for Chinese customers, multinationals need to adjust their overall sales and marketing strategies", Peng said. That reduced Apple's market share to 11.5 percent from 12.9 percent a year earlier, the report said. Overall industry shipments for China fell 9.7 per cent to 103 million units. That's despite grappling with an unusually turbulent few months during which its finance chief was arrested on allegations of bank fraud, and the USA marshalled its allies to try and block the company from selling next-generation networking equipment.
As per the IDC report, Apple was was ranked fourth by shipments in the country during the period, behind China's Huawei, Oppo and Vivo. But there's an unrelated reason, IDC says: Xiaomi suffered from "inventory corrections and an internal restructuring", the firm claims.
Lei Jun, Xiaomi's billionaire co-founder, is among those who expect the advent of 5G to energize demand.