Why is MKMapView delegate method not being called?

Question

I'm very new to iphone development and I'm trying to annotate a map. I've been able to get 3 location points on a map with hardcoded coordinates and now I'm trying to customize the pins. I know to do that you need to implement the:-(MKAnnotationView *)mapView:(MKMapView *)mV viewForAnnotation:(id <MKAnnotation>)annotation { delegate method.

For some reason I've been unable to even get it called. Here is what I have in the controller header:

#import "ArtPiece.h"
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>

@interface TestViewController : UIViewController <MKMapViewDelegate> {
    MKMapView *mapView;
    NSMutableArray *mapAnnotations;
    float results_lat[3];
    float results_long[3];
    NSMutableArray *results_title;
    NSMutableArray *Arts;

}
@property (nonatomic, retain) IBOutlet MKMapView *mapView;
@property (nonatomic, retain) NSMutableArray *mapAnnotations;

@end

And here is what I have in the controller implementation:

- (void)viewDidLoad {
    results_long[0] = -122.477989;
    results_lat[0] = 37.810000;
    results_long[1] = -122.480000;
    results_lat[1] = 37.820000;
    results_long[2] = -122.4850000;
    results_lat[2] = 37.830000;

    self.mapAnnotations = [[NSMutableArray alloc] initWithCapacity:3];
    Arts = [[NSMutableArray alloc] initWithCapacity:3];
    for(int x = 0; x<3; x++)
    {
        // creates an ArtPiece object and sets its lat and long
        ArtPiece *a = [[ArtPiece alloc] init];
        a.longitude = [NSNumber numberWithDouble:results_long[x]];
        a.latitude = [NSNumber numberWithDouble:results_lat[x]];
        a.title = @"please show up";
        // add objects to annotation array
        [self.mapAnnotations insertObject:a atIndex:x];
        [a release];

    }
    // center screen on cali area
    [self gotoLocation];
    for(int x = 0; x<3; x++)
    {
        [mapView addAnnotations:mapAnnotations];
    }
}

-(MKAnnotationView *)mapView:(MKMapView *)mV viewForAnnotation:(id <MKAnnotation>)annotation {
    NSLog(@"This is not printing to to console...");
    MKPinAnnotationView *pinView = nil; 
    if(annotation != mapView.userLocation) 
    {
        static NSString *defaultPinID = @"com.invasivecode.pin";
        pinView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:defaultPinID];
        if ( pinView == nil ) pinView = [[[MKPinAnnotationView alloc]
                                          initWithAnnotation:annotation reuseIdentifier:defaultPinID] autorelease];

        pinView.pinColor = MKPinAnnotationColorPurple; 
        pinView.canShowCallout = YES;
        pinView.animatesDrop = YES;
    } 
    else {
        [mapView.userLocation setTitle:@"I am here"];
    }
    return pinView;
}

And here is the ArtPiece class implementation:

   #import "TestViewController.h"
    #import "ArtPiece.h"
    #import <MapKit/MapKit.h>
    #import <CoreData/CoreData.h>

    @implementation ArtPiece

    @synthesize title, artist, series, description, latitude, longitude;

    - (CLLocationCoordinate2D)coordinate
    {
        CLLocationCoordinate2D theCoordinate;
        theCoordinate.latitude = [self.latitude doubleValue];
        theCoordinate.longitude = [self.longitude doubleValue];
        return theCoordinate;
    }



    @end

It's probably something simple. Is there something wrong with my method declaration? Did I declare the delegate wrong? I can't figure it out, again, I'm very new to this objective c/delegate stuff. Thanks for any help.

Answer 1

The addAnnotations method expects an NSArray of objects that conform to the MKAnnotation protocol.

You are adding objects of type ArtPiece which don't seem to implement MKAnnotation which has a coordinate property (not latitude and longitude properties).

Update your ArtPiece class to conform to MKAnnotation (or use the pre-defined MKPointAnnotation class). But updating your custom class is a better fix.