Here is a typical UIBarButtonItem created to display a refresh button in the navigation bar.

UIBarButtonItem *refreshItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshLogsAction:)];

self.navigationItem.rightBarButtonItem = refreshItem;

[refreshItem release];

Here’s how to change that button to a UIActivityIndicatorView custom UIBarButtonItem button.

- (void)refreshLogsAction:(id)sender;

{

    UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];

    [activityIndicator startAnimating];

    UIBarButtonItem *activityItem = [[UIBarButtonItem alloc] initWithCustomView:activityIndicator];

    [activityIndicator release];

    self.navigationItem.rightBarButtonItem = activityItem;

    [activityItem release];

    ... do something

}