I ended up with the same issue, and I struggled quite a bit to get it to work, so I will share the solution I found:
First, you should use the P4Server class instead of the Perforce.P4.Connection. They are two classes doing more or less the same thing, but when I tried using the P4.Connection.TaggedOutputReceived events, I simply got nothing back. So instead I tried with the P4Server.TaggedOutputReceived, and there, finally, I got the TaggedOutput just like I wanted.
So, here is a small example:
P4Server p4Server = new P4Server(cwdPath); //In my case I use P4Config, so no need to set user or to login, but you can do all that with the p4Server here.
p4Server.TaggedOutputReceived += P4ServerTaggedOutputEvent;
p4Server.ErrorReceived += P4ServerErrorReceived;
bool syncSuccess=false;
try
{
P4Command syncCommand = new P4Command(p4Server, "sync", true, syncPath + "\\...");
P4CommandResult rslt = syncCommand.Run();
syncSuccess=true;
//Here you can read the content of the P4CommandResult
//But it will only be accessible when the command is finished.
}
catch (P4Exception ex) //Will be caught only when the command has failed
{
Console.WriteLine("P4Command failed: " + ex.Message);
}
And the method to handle the error messages or the taggedOutput:
private void P4ServerErrorReceived(uint cmdId, int severity, int errorNumber, string data)
{
Console.WriteLine("P4ServerErrorReceived:" + data);
}
private void P4ServerTaggedOutputEvent(uint cmdId, int ObjId, TaggedObject Obj)
{
Console.WriteLine("P4ServerTaggedOutputEvent:" + Obj["clientFile"]); //Write the synced file name.
//Note that I used this only for a 'Sync' command, for other commands, I guess there might not be any Obj["clientFile"], so you should check for that.
}