Question

I have declared the following in my .h file:

Annotation *annoForMoreDetails.

However when I try to set it to the current annotation in the method

- (MKAnnotationView *)mapView:(MKMapView *)mapViews viewForAnnotation:(id <MKAnnotation> )annotation


It gets set to the wrong object.

Here is my code:

 - (MKAnnotationView *)mapView:(MKMapView *)mapViews viewForAnnotation:(id <MKAnnotation> )annotation
{
    NSLog(@"welcome into the map view annotation");
    // if it's the user location, just return nil.
    if ([annotation isKindOfClass:[MKUserLocation class]])
        return nil;
    for (annotation in [mapView annotations]) {
        if ([[mapView annotations] containsObject:annotation]) {
            annoForMoreDetails = annotation;
        }
    }
    if (annoForMoreDetails.coordinate.latitude != mapViews.userLocation.coordinate.latitude && annoForMoreDetails.coordinate.longitude != mapViews.userLocation.coordinate.longitude) {
    // try to dequeue an existing pin view first
    static NSString* AnnotationIdentifier = @"AnnotationIdentifier";
    MKPinAnnotationView* pinView = [[[MKPinAnnotationView alloc]
                                     initWithAnnotation:annotation reuseIdentifier:AnnotationIdentifier] autorelease];
    pinView.animatesDrop=YES;
    pinView.canShowCallout=YES;
    pinView.pinColor = MKPinAnnotationColorGreen;

    UIButton* rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
    [rightButton setTitle:annotation.title forState:UIControlStateNormal];
    [rightButton addTarget:self
                    action:@selector(moreDetails)
          forControlEvents:UIControlEventTouchUpInside];
    pinView.rightCalloutAccessoryView = rightButton;
    return pinView;
    }
    else if (annoForMoreDetails.coordinate.latitude == mapViews.userLocation.coordinate.latitude && annoForMoreDetails.coordinate.longitude == mapViews.userLocation.coordinate.longitude) {
        return nil;
    }
    return nil;
}

- (void)moreDetails {
    annotationCalloutView.frame = CGRectMake(70, 120, 188, 218);
    annotationCalloutView.alpha = 0.0;
    mapView.userInteractionEnabled = NO;
    annotationCalloutView.userInteractionEnabled = YES;
    titleLabel.text = annoForMoreDetails.title;
    titleLabel.numberOfLines = 0;
    titleLabel.userInteractionEnabled = NO;
    addressLabel.text = annoForMoreDetails.subtitle;
    [self.view addSubview:annotationCalloutView];
    [UIView beginAnimations:@"callout" context:NULL];
    [UIView setAnimationDuration:0.6];
    annotationCalloutView.alpha = 1.0;
    [UIView commitAnimations];
}

If you see anything wrong please point it out!

Answer 1

Are you trying to use annoForMoreDetails to know which annotation the user tapped on so you can show more details? If that’s the case, there’s an easier way. Use the map view’s calloutAccessoryControlTapped delegate method. It will be called when the user taps on the accessory button and it will pass the annotation view which includes the annotation as a property.

Remove the annoForMoreDetails instance variable and in viewForAnnotation, remove the for-loop that sets annoForMoreDetails (I think it ends up setting it to the last annotation every time). Remove all other references to annoForMoreDetails.

Also in viewForAnnotation, remove the addTarget line on the rightButton since you’ll replace your custom moreDetails method with an implementation of calloutAccessoryControlTapped:

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view 
    calloutAccessoryControlTapped:(UIControl *)control
{
    Annotation *annoForMoreDetails = (Annotation *)view.annotation;

    //the code currently in moreDetails method goes here...
}