Apple finally gets some good news in China as iPhone shipments surge

• Apple's iPhone shipments in China surged 40% in May, according to Bloomberg calculations.
• Shipments soared more than 50% in April, suggesting Apple is regaining ground in the key market.
• It had to slash prices and run big promotions to boost demand, putting profit margins at risk.

Apple appears to be reigniting iPhone demand in China, but its profit margins could pay the price.