I'm very interested in whether it works and, if so, how the system decides to enable or not TFO when working with the network using URLSession.
I didn't find any information in the documentation.
For example, for NWConnection we need to manually add additional option:
/* Allow fast open on the connection parameters */
parameters.allowFastOpen = true
let connection = NWConnection(to: endpoint, using: parameters)
/* Call send with idempotent initial data before starting the connection */
connection.send(content: initialData, completion: .idempotent)
connection.start(queue: myQueue)
AFAICT URLSession has no TFO support.
Speaking personally, TFO seems like a bit of a dead end to me, and if you’re interested in HTTP performance than HTTP/3 (on QUIC) is the way forward.
However, if there’s a specific reason that TFO is critical to your product then you should file an enhancement request explaining that. Please post your bug number, just for the record.
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