The correct order of exchaging session description and ICE candidate

[daweifeng]

Hi!

I have been wondering about the correct order of exchaging session description and ICE candidate. When we create an offer, I feel like we should set local description after sending out the offer. Because when we set an local description, it starts the ICE gathering and the gathered ICE candidates could be sent to the peer. By setting local description after sending out the offer, we can make sure that the ICE candidates arrive at the peer after the offer. However, if we set local description before sending out the offer, there could be a race condition that the ICE candidates arrvie earilier than the offer and the remote peer could not handle them because it does not have an offer....

When I look at examples in this project and examples on Google, it seems like people always set local description before sending out the offer. Is there any reason behind it? Or maybe my understanding above is not correct?

Thank you!