如何从XMPP服务器获取所有联系人

Question

我正在开发IOS上的聊天应用程序，我正在尝试从XMPP服务器获取联系人，但突然间我无法从XMPP服务器获取任何联系人。 我正在使用以下代码从服务器获取联系人：

(IBAction)sendRequest:(id)sender 
{
     self.btnContacts.userInteractionEnabled=false;
     [self disableUI];
     //To Search Peticular User either by using their name, email or username
     NSString *userBare1  = [[[[self appDelegate] xmppStream] myJID] bare];
     NSXMLElement *query = [NSXMLElement elementWithName:@"query"];
     [query addAttributeWithName:@"xmlns" stringValue:@"jabber:iq:search"];

     NSXMLElement *x = [NSXMLElement elementWithName:@"x" xmlns:@"jabber:x:data"];
     [x addAttributeWithName:@"type" stringValue:@"submit"];

     NSXMLElement *formType = [NSXMLElement elementWithName:@"field"];
     [formType addAttributeWithName:@"type" stringValue:@"hidden"];
     [formType addAttributeWithName:@"var" stringValue:@"FORM_TYPE"];
     [formType addChild:[NSXMLElement elementWithName:@"value" stringValue:@"jabber:iq:search" ]];

     NSXMLElement *userName = [NSXMLElement elementWithName:@"field"];
     [userName addAttributeWithName:@"var" stringValue:@"Username"];
     [userName addChild:[NSXMLElement elementWithName:@"value" stringValue:@"1" ]];

     NSXMLElement *name = [NSXMLElement elementWithName:@"field"];
     [name addAttributeWithName:@"var" stringValue:@"Name"];
     [name addChild:[NSXMLElement elementWithName:@"value" stringValue:@"1"]];

     NSXMLElement *email = [NSXMLElement elementWithName:@"field"];
     [email addAttributeWithName:@"var" stringValue:@"Email"];
     [email addChild:[NSXMLElement elementWithName:@"value" stringValue:@"1"]];

     //Here in the place of SearchString we have to provide registered user name or emailid or username(if it matches in Server it provide registered user details otherwise Server provides response as empty)
     NSXMLElement *search = [NSXMLElement elementWithName:@"field"];
     [search addAttributeWithName:@"var" stringValue:@"search"];
     [search addChild:[NSXMLElement elementWithName:@"value" stringValue:[NSString stringWithFormat:@"%@",@"*"]]];

     [x addChild:formType];
     [x addChild:userName];
     [x addChild:name];
     [x addChild:email];
     [x addChild:search];
     [query addChild:x];

     NSXMLElement *iq = [NSXMLElement elementWithName:@"iq"];
     [iq addAttributeWithName:@"type" stringValue:@"set"];
     [iq addAttributeWithName:@"id" stringValue:@"searchByUserName"];
     [iq addAttributeWithName:@"to" stringValue:[NSString stringWithFormat:@"search.%@",@"server name"]];
     [iq addAttributeWithName:@"from" stringValue:userBare1];
     [iq addChild:query];
     [[[self appDelegate] xmppStream] sendElement:iq];
}