request help/tutorial-MapKit with callout accessory button shows details of the pin

#import \"MapViewController.h\"
#import \"DetailViewController.h\"
#import \"BridgeAnnotation.h\"

enum
{
    kCityAnnotationIndex = 0,
    kBridgeAnnotationIndex
};

@implementation MapViewController

@synthesize mapView, detailViewController, mapAnnotations;


#pragma mark -

+ (CGFloat)annotationPadding;
{
    return 10.0f;
}
+ (CGFloat)calloutHeight;
{
    return 40.0f;
}

- (void)gotoLocation
{
    // start off by default in San Francisco
    MKCoordinateRegion newRegion;
    newRegion.center.latitude = 37.786996;
    newRegion.center.longitude = -122.440100;
    newRegion.span.latitudeDelta = 0.112872;
    newRegion.span.longitudeDelta = 0.109863;

    [self.mapView setRegion:newRegion animated:YES];
}

- (void)viewDidAppear:(BOOL)animated
{
    // bring back the toolbar
    [self.navigationController setToolbarHidden:NO animated:NO];
}

- (void)viewDidLoad
{
    self.mapView.mapType = MKMapTypeStandard;   // also MKMapTypeSatellite or MKMapTypeHybrid

    // create a custom navigation bar button and set it to always says \"Back\"
	UIBarButtonItem *temporaryBarButtonItem = [[UIBarButtonItem alloc] init];
	temporaryBarButtonItem.title = @\"Back\";
	self.navigationItem.backBarButtonItem = temporaryBarButtonItem;
	[temporaryBarButtonItem release];
    
    // create out annotations array (in this example only 2)
    self.mapAnnotations = [[NSMutableArray alloc] initWithCapacity:2];
    
        // annotation for Golden Gate Bridge
    BridgeAnnotation *bridgeAnnotation = [[BridgeAnnotation alloc] init];
    [self.mapAnnotations insertObject:bridgeAnnotation atIndex:kBridgeAnnotationIndex];
    [bridgeAnnotation release];
    
    [self gotoLocation];    // finally goto San Francisco
}

- (void)viewDidUnload
{
    self.mapAnnotations = nil;
    self.detailViewController = nil;
    self.mapView = nil;
}

- (void)dealloc 
{
    [mapView release];
    [detailViewController release];
    [mapAnnotations release];
    
    [super dealloc];
}


#pragma mark -
#pragma mark ButtonActions

- (IBAction)bridgeAction:(id)sender
{
    [self gotoLocation];
    [self.mapView removeAnnotations:self.mapView.annotations];  // remove any annotations that exist
    
    [self.mapView addAnnotation:[self.mapAnnotations objectAtIndex:kBridgeAnnotationIndex]];
}

#pragma mark -
#pragma mark MKMapViewDelegate

- (void)showDetails:(id)sender
{
    // the detail view does not want a toolbar so hide it
    [self.navigationController setToolbarHidden:YES animated:NO];
    
    [self.navigationController pushViewController:self.detailViewController animated:YES];
}

- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation
{
    // if it's the user location, just return nil.
    if ([annotation isKindOfClass:[MKUserLocation class]])
        return nil;
    
    // handle our two custom annotations
    //
   else // for Golden Gate Bridge
    {
        // try to dequeue an existing pin view first
        static NSString* BridgeAnnotationIdentifier = @\"bridgeAnnotationIdentifier\";
        MKPinAnnotationView* pinView = (MKPinAnnotationView *)
                                        [mapView dequeueReusableAnnotationViewWithIdentifier:BridgeAnnotationIdentifier];
        if (!pinView)
        {
            // if an existing pin view was not available, create one
            MKPinAnnotationView* customPinView = [[[MKPinAnnotationView alloc]
                                             initWithAnnotation:annotation reuseIdentifier:BridgeAnnotationIdentifier] autorelease];
            customPinView.pinColor = MKPinAnnotationColorPurple;
            customPinView.animatesDrop = YES;
            customPinView.canShowCallout = YES;
            
            // add a detail disclosure button to the callout which will open a new view controller page
            //
            // note: you can assign a specific call out accessory view, or as MKMapViewDelegate you can implement:
            //  - (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control;
            //
            UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
            [rightButton addTarget:self
                            action:@selector(showDetails:)
                  forControlEvents:UIControlEventTouchUpInside];
            customPinView.rightCalloutAccessoryView = rightButton;

            return customPinView;
        }
        else
        {
            pinView.annotation = annotation;
        }
        return pinView;
    }
        
    return nil;
}

@end