XMPPFrameWork TurnSocket can be used?

Question

The XMPPFrameWork TurnSocket can be use?? I want to use the TurnSocket to transmit file,but failed, the call back math run into "- (void)turnSocketDidFail:(TURNSocket *)sender" every time. but i can use the ejabberd server to transmit file by iChat and Adium. who can use the TurnSocket class to transmit file, please help me, please send a email to me if you can ,my email is 182459312@qq.com. thanks. there is my code.

    BOOL bCon = [_xmppStream isConnected];
    //bCon is YES.

    NSArray * array = [NSArray arrayWithObjects:@"proxy.eu.jabber.org", nil]; 
//NSArray * array = @[@"conference.mini.local", @"pubsub.mini.local", @"vjud.mini.local"];
//my host server is "mini.local", there array 
//what's i can use to the array? i test everyone... @[@"mini.local"]  or //@[@"conference.mini.local", @"pubsub.mini.local", @"vjud.mini.local"]
// or @[@"proxy.eu.jabber.org"] but failed!
    [TURNSocket setProxyCandidates: array];

    XMPPJID *jid = [XMPPJID jidWithString : @"test2@mini.local" ];//@"test2@mini.local" is 
    //the target user who want get file.
    _objTURNSocket = [[TURNSocket alloc] initWithStream:_xmppStream toJID:  jid ];
    [_objTURNSocket startWithDelegate:self delegateQueue:dispatch_get_main_queue() ];

but when i was run,the call back math "- (void)turnSocketDidFail:(TURNSocket *)sender" was called.....