Apple's reliance on the country is now being put to the test. On a conference call with analysts after its Tuesday earnings report, Cook said the company is beginning to see "economic softness" in the region, particularly in Hong Kong.

China is no longer able to offset sluggishness elsewhere or counter the broader slowdown in the global smartphone market.

Even with the Chinese New Year shopping season approaching, Apple is projecting its first quarterly sales decline since 2003.

“You need to take into account the business opportunities that we have but also the realities of an economic environment that is not ideal right now,” said Luca Maestri, Apple's chief financial officer, noting that sales in Brazil, Canada, Japan, and Russia also are being affected by global economic malaise.

Cook remains optimistic about China and vowed that Apple will invest through any downturn. And given the company's resources (there's still a whopping $216 billion on its balance sheet), he has the luxury of playing the long game. It has 28 stores in mainland China now and will have 40 by this summer.

"We believe that this, too, shall pass," Cook said. "We aren't retrenching. We don’t believe in that. We are fortunately strong enough to continue investing, and we think it's in Apple's long- term interest to do so."

Eoin Treacy's view

Weak Chinese demand amid a slowing economy and falling currency represent headwinds for Apple, not least because China has been its primary growth engine over the last couple of years. The commitment to continue to expand in China is a welcome decision but is likely to be overshadowed by the company’s buyback program. 

The share moved to a new closing low today and a clear upward dynamic will be required to signal support has been found in the region of the August low. 

Despite a drop of over 25% in the last year, Apple is still the world’s largest share and its underperformance has a bearish influence on the wider market. The S&P 500 bounced last week from the region of 1800 but pulled back sharply today and the low will need to hold if ranging is to be given the benefit of the doubt. 

The Nasdaq-100 has also lost uptrend consistency and the low near 4000 needs to hold if potential for higher to lateral ranging is to remain credible. 

The Russell 2000 is oversold relative to the trend mean but its bounce to date has been unimpressive and it will need to hold the 1000 level to avoid an even larger overextension forming.