UIBarButtonItem *flexItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

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

refreshItem.style = UIBarButtonItemStylePlain;

NSArray *items = [NSArray arrayWithObjects: flexItem, refreshItem, nil];

[toolbar setItems:items animated:NO];

Then by default with that code it would display a refresh button at the right hand side of the toolbar, and when clicking on it would call refreshAction:(id)sender.  To be helpful to the end user we might want to change the refresh button to an activity indicator whilst the refresh action was taking place.

The first job is to make the refresh button and flex item a global property so you can call them from different place.  Now we also need to create a UIActivityIndicator.

When the refresh action starts you can call the following code to display the activity indicator

CGRect frame = CGRectMake(0.0, 0.0, 25.0, 25.0);

UIActivityIndicatorView *loading = [[UIActivityIndicatorView alloc] initWithFrame:frame];

[loading sizeToFit];

loading.autoresizingMask = (UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin);

[loading startAnimating];

UIBarButtonItem *statusInd = [[UIBarButtonItem alloc] initWithCustomView:loading];

statusInd.style = UIBarButtonItemStylePlain;

NSArray *items = [NSArray arrayWithObjects: flexItem, statusInd, nil];

[toolbar setItems:items animated:NO];

Then when the refresh action stops, simply call the following, as we’ve already made flexItem and refreshItem a global property we don’t need to redefine them or re-point them to their action selector.

NSArray *items = [NSArray arrayWithObjects: flexItem, refreshItem, nil];

[toolbar setItems:items animated:NO];

[UIApplication sharedApplication].applicationIconBadgeNumber = 10;