Instead of adding the UILabel and UIActivity indicator on the tableview in the nib, I suggest you add them to the view containing the tableview by adding them in viewDidLoad or an appropriate method of your view controller.
e.g.
UIActivityIndicator activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
[activityIndicator setCenter:CGPointMake(160,200)];
[self.view addSubview:activityIndicator];
Similarly you can add the label and position it in the view.
You can then add
[activityIndicator startAnimating];
and
[activityIndicator stopAnimating];
wherever you want the spinner to start or stop animating. I am not sure what you want to do with the label. If its to display a loading message, you can make the label hidden or visible as appropriate.