Gene Cao, an analyst with Forrester Research, a market research firm, said since Apple has already stocked up on sufficient inventories, maintaining a large manufacturing workforce has become costly for supply chain manufacturers. "Apple's new iPhone inventories are more than sufficient for requirements in key markets around the world."

"In addition, because Apple only updated a few features in its latest flagship, many users are reluctant to replace their devices for a device that lacks in innovation," he said, adding the unsatisfactory performance of the iPhone's new chips also hurt the company's sales.

At the manufacturing facility, it is the poor working conditions that have been responsible for the exits of some workers, Cao said.

Tech website cnet.com said 58 percent of the workers at Pegatron's factories were working in excess of the Apple-stipulated 60 hours a week. Overtime－which is supposed to be voluntary－was mandatory at Pegatron, the report said.

Cai Xiaoshuai left his hometown in Luoyang of Henan province and landed a job at the assembly line in Pegatron four months ago. But the 22-year-old man said he had had enough. His basic wage was 2,020 yuan ($320) per month and he had to work overtime for 2.5 hours every day to make sure that his salary would get close to 4,000 yuan.

"Some of my friends went to Kunshan in Jiangsu province to try their luck there. But it seems that the electronics industry there is in an even worse shape. So I am thinking of staying on and checking out other opportunities in Shanghai. But I will definitely not work in any electronics company. I have had enough," said Cai.