The 'collapse' is concerning the CNY, or 'external' Yuan. It's down a bit more, but it's certainly no collapse.
China's economy is currently in depression. The value of the Yuan is not particularly related to that, other than the higher inflation that usually (but not always) accompanies such a depression. The government, since it owns the steel and concrete industries, is trying to build it's way out it's problems, instead of just printing money like we do. This is why you see grandiose building projects in China, including whole cities that no one lives in.
It won't work, of course.
Trump's tariffs only add to the problems in China, and are only in response to China's tariffs on US imports to China. China will lose this trade war. They don't have anywhere near the resources the U.S. does, and their people aren't spending money. Money velocity in China is almost nil. Their people are saving like mad for their retirement, because their government has no retirement program.
Not really much different than both Partys here trying to gin up one real estate bubble after another, then telling people how wonderful it is $30,000 houses now sell for $500,000 or whatever and they should run out and borrow all they can against the 'equity' and spend it on crap. then when it bursts flood the bankruptcy courts and do it all over again 3 years later.