The iPhone 6 (left) and iPhone 6 Plus (middle) are stealing market share away from Google. On the right in the photo is the iPhone 5s. Image source: Flickr user Kārlis Dambrāns

The good news continues for Apple (AAPL 0.64%) in regards to its smartphone line. After releasing its newest iterations of the iPhone last September -- the iPhone 6 and iPhone 6 Plus -- the company has experienced tremendous demand for the product, culminating in a record-breaking first fiscal quarter in which the company reported $18 billion in net income.

Look beyond the headline numbers, and the story of Apple's year-over-year growth becomes a little clearer. The company grew revenue an astonishing 30% year over year, mostly on the back of 70% growth in China. Matter of fact, China provided 40% of Apple's total revenue growth during this period -- for simplicity, $4 out of every $10 above last year's revenue total came courtesy of Apple's Middle Kingdom operations.

So for investors, China is becoming increasingly important to Apple as a growth story and should be watched closely. And if Kantar Worldpanel's newest survey is correct, Apple continues to execute well there.

Continued growth in urban China at the expense of Google's Android
 Data from market researcherKantar show increasing adoption for Apple in urban China. Kantar reports Apple's market share for the three months ended February at 27.6% to Google's Android take at 70.9%. Of course, analysts don't expect parity considering Google offers a disparate selection of phone units at a host of price points while Apple only focuses on the high end. As an example, domestic vendor Xiaomi has made incredible strides in China with its low-cost Apple-inspired Google OS phones.

But, there's a decidedly strong trend toward Apple adoption. Compare its recent current 27.6% market share to the three months ended in December, when Apple accounted for a 21.5% market share to Android's 77%. The month the iPhone 6 was released in China -- October -- found Apple with a 15.7% market share to 82.9% for Android. Notice a trend here?  Apple's added 11.9 percentage points of market share in China since October while Android has lost 12 percentage points.

The worldwide story is similar, to a lesser degree
The worldwide iPhone market share story is reflective of Apple's Chinese story, albeit to a lesser degree. On a year-over-year basis, for the three months ended February 2015, Apple grew in seven out of the nine markets surveyed with the home market of the United States registering a curious but comparatively small loss of 0.5 percentage points while registering a loss of 5.1 percentage points in Japan -- in both of those markets Android increased its market share.

However, the other seven markets showed increased demand, on a relative basis, for Apple's signature product. In the EU5 (a group that includes Germany, Great Britain, France, Italy, and Spain), Apple's market share increased 2.9 percentage points to 20.9% while Android dropped a corresponding 2.9 percentage points to 67.6%. The standout performer for Apple was Great Britain, which grew 8.6 percentage points and has a market share (38.6) similar to the U.S. (38.8) and Australia (38.5).

Long story short, Apple continues to execute worldwide in its most important product. For long-term investors, you have to be happy with Kantar's report.

Editor's note: This article has been updated to note that Kantar's research covers urban China.