This may be a design error instead of a syntax error, so let me know if I'm coding in the wrong direction here.
I'm new to Cocoa Touch/Objective-C and I've been working through tutorials on Core Data and MapKit. So far the app places an annotation on a mapview for items fetched from Core Data. I made a custom annotation object (called MapPin) that also holds a URI (NSURL*) pointing to the object in Core Data that it represents. When the user selects an annotation I want to use the URI property of that annotation to find which object in coredata the annotation represents.
This works if I add the annotation to the mapview beforehand. Here I add a MapPin annotation for each object "thing"
//viewWillAppear function in my ViewController
NSURL *uri = [[thing objectID] URIRepresentation];
MapPin *annotation = [[[MapPin alloc] initWithName:thing.common description:thing.latin coordinate:coordinate uri:uri] autorelease];
NSLog(@"MapPin URI: %@", [annotation.uri absoluteString]); //This works!
[_mapView addAnnotation:annotation];
NSLog(@"Placed Map Pin: %@", thing.common);
Later, after the user selects an annotation and clicks a button in the annotationView callout, I want to access the URI for the selected annotation
//the UIButton click action in my view controller
MSPTreesAppDelegate *del = (MSPTreesAppDelegate *)[UIApplication sharedApplication].delegate;
NSArray *annArray = _mapView.selectedAnnotations;
MapPin *selectedPin = [annArray objectAtIndex:0];
NSLog(@"Selected Pin Name: %@", selectedPin.name); //Works fine
NSLog(@"URI PASSED: %@", [selectedPin.uri absoluteString]); //Doesn't work
NSURL* uriForTree = selectedPin.uri; //also doesn't work
I notice in the debugger that before I add the annotation to the mapview, the URI property shows the correct string. After the (MapPin) annotation is selected from the map view, the URI property in the debugger just shows "invalid summary".
When I try to access the URI property the program ends and I get a "Thread 1: Program Received signal: "EXC_BAD_ACCESS"." error. The Log doesn't show anything helpful besides that.
I assume that my custom URI property for my MKAnnotation object isn't supported by the MKAnnotationView or the MKMapView, but I can't figure out where the URI is getting lost. Is there a way I can retrieve my URI property from the selected annotation? Other suggestions for methods to accomplish the same concept are welcome.
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation {
static NSString *identifier = @"MapPin";
if ([annotation isKindOfClass:[MapPin class]]) {
NSLog(@"Annotation is a MapPin");
TreeAnnotationView *annotationView = (TreeAnnotationView *) [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if (annotationView == nil) {
annotationView = [[TreeAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
} else {
annotationView.annotation = annotation;
}
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
//Place details button in callout
UIButton * detailButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[detailButton setTitle:annotation.title forState:UIControlStateNormal];
[detailButton addTarget:self action:@selector(showDetails:) forControlEvents:UIControlEventTouchUpInside];
annotationView.rightCalloutAccessoryView = detailButton;
return annotationView;
}
return nil;
}
