如何在iPhone中多次调用的方法中仅推一次视图

Question

 - (void)xmppStream:(XMPPStream *)sender didReceiveMessage:(XMPPMessage *)message
{
       ChatViewController *chatView;
       if(contactView==nil)
       {                
       chatView=[[ChatViewController alloc] initWithNibName:@"ChatViewController" bundle:nil];
        }   
       [self.navigationController pushViewController:chatView animated:YES];
       [messageDelegate newMessageReceived:m]; 
}

The above delegate method called for every incoming message.When it called, it goes to a new UIViewController.Here my problem is a view pushed multiple tinmes,so error will be occered.how can i fix this error in iphone

Answer 1

Add this snippet before pushing the view controller

BOOL viewControllerAlreadyPushed = NO;
for (UIViewController *controller in self.navigationController.viewControllers) {
    if ([controller isKindOfClass:[ChatViewController class]]) {
        viewControllerAlreadyPushed = YES;
    }
}

if(!viewControllerAlreadyPushed) //if not pushed, push it
{
    ChatViewController *chatView;
    if(contactView==nil)
    {                
        chatView=[[ChatViewController alloc] initWithNibName:@"ChatViewController" bundle:nil];
    }   
    [self.navigationController pushViewController:chatView animated:YES];
    [messageDelegate newMessageReceived:m]; 
}