A model displays a newly launched Xiaomi Mi 4i phone in Hong Kong. Reuters

China can lay claim to the world’s largest smartphone market, and sales of iPhone 6 and iPhone 6 plus have surged there in the wake of their recent release. Yet, overall, for the first time in six years, sales of smartphones are in decline.

Smartphone shipments fell 4.3 percent in the first quarter compared with the same period in the previous year, according to an IDC survey obtained by the Wall Street Journal.

Linda Sul, director at Strategy Analytics, confirmed the slowdown. “China smartphone growth on an annualized basis has slowed from 39 percent to 17 percent during the past year, due to increasing penetration maturity,” she wrote in a press release. “This is the first quarter that China's smartphone annual growth rate has been lower than the global average since 2010.”

Apple took the top spot in China for market share, followed by Xiaomi and Huawei. Samsung, which ranked No. 1 in the first quarter a year go, fell to fourth place. The share of all other manufacturers fell to 64.7 percent, down from 71.9 percent in the year-ago period, according to Strategy Analytics.

Despite China's growing middle class, the increased mobile penetration in the country could force makers of smartphones to rely increasingly on upgraders for future sales. “The smartphone market in China is basically now just the very high end like Apple or the very low end,” Charles Lin, chief financial officer of Pegatron Corp., told the Wall Street Journal. “It’s getting tough for those in the middle.”

As a result, some manufacturers, such as ZTE, have gone upscale in their offerings, reports IDG, adding features more often seen on premium smartphones, a market currently dominated by the Apple.