Добавьте UIActivityIndicatorView
как подпредставление кнопки:
// Create spinner
UIActivityIndicatorView *myIndicator = [[UIActivityIndicatorView alloc]
initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
// Position the spinner
[myIndicator setCenter:CGPointMake(myButton.frame.size.width / 2, myButton.frame.size.height / 2)];
// Add to button
[myButton addSubview:myIndicator];
// Start the animation
[myIndicator startAnimating];