Apple's hottest products are facing significant demand in China, with the 11-inch MacBook Air, certain versions of the iPad, and the iPhone 4 all facing shortages.

Analyst Brian White with Ticonderoga Securities is continuing his tour of the Far East, and on Monday provided investors an update on his second day in China. Though he noted the iPad and 11-inch MacBook Air, in particular he found the iPhone 4 to be Apple's most difficult product to purchase.

He said wait times are around two months and carrier China Unicom is unable to fulfill about a third of preorders. Apple's interest in the market is seen as positive because of the growth opportunities in China.

"Most of the carriers agree that the high-end smartphone opportunity in China is approximately 100-125 million subscribers, which we view as the addressable market for the iPhone," White wrote.

The iPhone 4 debuted on network China Unicom in September, and posted strong sales of 100,000 in its first four days. Since then, limited supply has led to extensive scalping, which forced Apple to require reservations for iPhone buyers.

Though China Mobile is not an official iPhone carrier, White said he believes it has the most iPhones on its network with about 2 million. To help capitalize on that, the carrier plans a tenfold increase in mobile application developers in the first quarter of 2011.

In November, China Mobile set up a website to help users trim their SIM card to fit inside the iPhone 4, which requires a microSIM. The carrier indicated to White it has plans to create a SIM card that will work with the iPhone 4.

Finally, Chinese CDMA-based carrier China Telecom is also viewed as a potential partner for Apple. White said he believes the company is "well positioned" to begin selling the iPhone in 2011.