连接服务器前需准备事项：

1.搭建好XMPP服务器

2.设置服务器地址和端口  

[_xmppStream setHostName:@"127.0.0.1"];

[_xmppStream setHostPort:5222];

3.调用connect

关键项：

　　JID－格式必须为 "用户名"+"@"+"服务器地址",示例 :[email protected]

　　　　　连接服务器必须进行JID设置，如果还没有账号可以设置任意值

具体代码如下：

- (BOOL)connect:(NSString*)user withpassWord:(NSString*)pwd
{  

if (user != nil) {
    user = [NSString stringWithFormat:@"%@@%@",user,_xmppStream.hostName];
    }
    if (![_xmppStream isDisconnected]) {
        if(_isLogined){
            NSError *error = nil;
            password=pwd;
            [[self xmppStream] setMyJID:[XMPPJID jidWithString:user  resource:@"ios"]];
            if (![[self xmppStream] authenticateWithPassword:password error:&error])
            {
                NSLog(@"Error authenticating: %@", error);
            }
        }
        return YES;
    }
    NSString *myJID = user;
    NSString *myPassword = pwd;
        if ( myPassword != nil) {
        password = myPassword;
    }
    if (myJID != nil) {
    
        [_xmppStream setMyJID:[XMPPJID jidWithString:myJID resource:@"ios"]];
    }else{
        [_xmppStream setMyJID:[XMPPJID jidWithString:_xmppStream.hostName resource:@"ios"]];
    }
    NSError *error = nil;
    [_xmppStream connectWithTimeout:10 error:&error];
    if(error)
    {
        NSLog(@"连接失败%@",error);
    }
    
    return YES;
}

连接返回的回调结果

///连接成功
- (void)xmppStreamDidConnect:(XMPPStream *)sender
{
    NSLog(@"连接成功");
    isXmppConnected = YES;
    if(_isLogined){
        NSError *error = nil;
        if (![[self xmppStream] authenticateWithPassword:password error:&error])
        {
            NSLog(@"Error authenticating: %@", error);
        }
    }
}
///连接失败
- (void)xmppStreamDidDisconnect:(XMPPStream *)sender withError:(NSError *)error
{
    NSLog(@"连接断开");
    
    if (!isXmppConnected)
    {
        //DDLogError(@"Unable to connect to server. Check xmppStream.hostName");
    }
}

断开连接

 [_xmppStream disconnect];