Hello Gianluca,
My Code is :
- (void)connectWithLightStreamer
{

fieldNames = [NSArrayarrayWithObjects:LIGHTSTREAMER_FIELDNAMES, nil];
[selfperformSelectorInBackground:@selector(connectInBackground) withObject:nil];

}
- (void) connectInBackground
{
_client = [[LSClientalloc] init];
LSConnectionInfo *connectioninfo = [LSConnectionInfo connectionInfoWithPushServerURL:LIGHTSTREAMER_CONNECITON_ADDRESS pushServerControlURL:nil user:@"username" password:@"password" adapter:LIGHTSTREAMER_CONNECITON_ADAPTER];
[_clientopenConnectionWithInfo:connectioninfo delegate:self];
}
- (void) clientConnectionLSClient *)client didReceiveServerFailureLSPushServerException *)failure {


[_clientperformSelectorInBackground:@selector(closeConnection) withObject:nil];

}

but i receive error : Thread 8:signal SIGABRT