That's a very big question. China has exchange controls, but only for residents of China. If you have access to Hong Kong, which the rest of the world does, you can exchange yuan for other currencies at market rates.

China's exchange controls are leaking at the rate of about $500bn a year.

It's worrisome that China's rich people want to get their money out of China. China is growing faster than the dollar or euro zones. Yet rich people in China are overpaying for US and UK real estate. What do they think is going to go wrong in China?