China owes Iran 22 billion dollars for the purchase of oil over the last number of years.
The question is: will China repay its entire debt to Iran?
In my opinion its unlikely. Iran would be lucky if it gets part of it.
Transferring billions of dollars to Iran could anger the US which is trying to impose sanctions against Iran. It’s unlikely that China will want to risk its relations with the U.S over Tehran. Its simply not worth their while.
China has bigger concerns, such as its sea dispute with the Philippines (as well as other neighbors) which the U.S is getting involved in. This is just one issue, among many which is more important to China than the Iranian government’s financial problems.