If it's every non-Chinese company doing business in China seeing slowed Chinese growth (or even reduced Chinese demand), then it's pretty clear that China's market is the problem and not Apple.

In this case, it's not just Apple and Samsung. It's a great many other industries, especially luxury goods, that have seen large drops in Chinese consumer demand.

> why hasn't Samsung's share price suffered as much as Apple's?

Samsung’s and Apple’s stocks are apples and oranges. iPhone is a principal value driver for Apple. Small swings in iPhone demand mean big swings in Apple value. Samsung, on the other hand, is a diversified conglomerate. Moreover, Apple is—corporate structure-wise, for an investor—simple. Single Delaware corporation priced in U.S. dollars and traded in New York. Samsung is a chaebol. Lots of interlocking entities and agreements, parts of which are listed in Korea.

Share price and a company doing well is only slightly correlated.

China is a big part of Apple's growth strategy.