MKAnnotationView pin wont appear - iphone

Question

I am new with MapKit and all its functionalities and therefore, stuck at trying to display a pin. I followed an online video tutorial on how to find user current location and drop a pin there. But when I typed the method for the pin, I do not get it at all. I would like to know where did I go wrong for this.
- (void)viewDidLoad{
[super viewDidLoad];
self.title = #"Location";
mapView.showsUserLocation = YES;
self.locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
[locationManager startUpdatingHeading];
}
-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation{
NSLog(#"Annotation view run");
MKPinAnnotationView *pin = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:#"currentloc"];
pin.animatesDrop = YES;
return pin;
}
-(void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{
// once location is determined, center to that location.
location = newLocation.coordinate;
MKCoordinateRegion region;
region.center = location;
MKCoordinateSpan span;
span.latitudeDelta = 0.003;
span.longitudeDelta = 0.003;
region.span = span;
[mapView setRegion:region animated:FALSE];
}
Any advice of where I done wrong would be great!

Answer 1

As your method is never got invoked, you should do:
- (void)mapView:(MKMapView *)aMapView regionDidChangeAnimated:(BOOL)animated {
[aMapView removeAnnotation:[self point]];
mkShape.coordinate = aMapView.centerCoordinate;
[aMapView addAnnotation:mkShape];
}
And you should create your MKAnnotationView properly.
You need create two properties in .h file first (for performance reason):
MKPointAnnotation *mkShape;
MKAnnotationView *annotationView;
then use the code below to create your MKPointAnnotation
- (void)createShape
{
if (!mkShape) {
mkShape = [[MKPointAnnotation alloc] init];
mkShape.title = nil;
mkShape.subtitle = #"test description";
}
}
- (id <MKAnnotation>)point
{
[self createShape];
// Make sure to check if this is an MKPointAnnotation. MKOverlays also
// conform to MKAnnotation, so it isn't sufficient to just check to
// conformance to MKAnnotation.
if ([mkShape isKindOfClass:[MKPointAnnotation class]])
return (id <MKAnnotation>)mkShape;
return nil;
}
- (MKAnnotationView *)annotationView
{
if (!annotationView) {
id <MKAnnotation> annotation = [self point];
if (annotation) {
MKPinAnnotationView *pin =
[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil];
pin.canShowCallout = YES;
pin.animatesDrop = YES;
pin.draggable = NO;
annotationView = pin;
}
}
return annotationView;
}
- (MKAnnotationView *)mapView:(MKMapView *)aMapView viewForAnnotation:(id <MKAnnotation>)annotation
{
if ([annotation isEqual:mkShape]) {
return [self annotationView];
}
return nil;
}
At the end, don't forget to release your properties.
- (void)dealloc
{
[annotationView release];
[mkShape release];
[super dealloc];
}