Using AVSpeechSynthesizer to read a description of location on a Map

Question

My map has 4 or 5 points close to each other and right now using AVSpeechSynthesizer I've got it so that it will say the name of the location (which is also displayed in a little bubble).

I want it to still show that bubble but when clicked I want it to say a description of that place that I would have specified. This is my code at the moment:

MapViewAnnotation.h

@interface MapViewAnnotation : NSObject <MKAnnotation> {
    NSString *title;
    CLLocationCoordinate2D coordinate;
    NSString *desc;
}

@property (nonatomic, copy) NSString *title;
@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
@property (nonatomic, readonly) NSString *desc;

- (id)initWithTitle:(NSString *)ttl andCoordinate:(CLLocationCoordinate2D)c2d initWithDesc:(NSString *)dsc;

MapViewAnnotation.m

@implementation MapViewAnnotation

@synthesize title, coordinate, desc;

- (id)initWithTitle:(NSString *)ttl andCoordinate:(CLLocationCoordinate2D)c2d initWithDesc:(NSString *)dsc {
[super init];
title = ttl;
coordinate = c2d;
    desc = dsc;
    return self;

MapViewController.h

@interface MapViewController : UIViewController {
    MKMapView *mapView;

}

@property (nonatomic, retain) IBOutlet MKMapView *mapView;
@property (strong, nonatomic) AVSpeechSynthesizer *synthesizer;

MapViewController.m

- (void)viewDidLoad
{

    // Set some coordinates for our position : Cutty Sark
    CLLocationCoordinate2D location;
    location.latitude = (double) 51.482997;
    location.longitude = (double) -0.010072;

    // Royal Observatory
    CLLocationCoordinate2D twoLocation;
    twoLocation.latitude = (double) 51.477805;
    twoLocation.longitude = (double) -0.001430;

    //Royal Naval College
    CLLocationCoordinate2D threeLocation;
    threeLocation.latitude = (double) 51.483344;
    threeLocation.longitude = (double) -0.006799;

    //Queen's House
    CLLocationCoordinate2D fourLocation;
    fourLocation.latitude = (double) 51.481383;
    fourLocation.longitude = (double) -0.003722;

    //National Maritime Museum
    CLLocationCoordinate2D fiveLocation;
    fiveLocation.latitude = (double) 51.481050;
    fiveLocation.longitude = (double) -0.005578;


    // Add Cutty Sark annotation to MapView
    MapViewAnnotation *newAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"Cutty Sark" andCoordinate:location initWithDesc:@"Description about Cutty Sark"];
    [self.mapView addAnnotation:newAnnotation];
    self.mapView.delegate = self;
    [newAnnotation release];


    // Add Royal Observatory annotation to MapView
    newAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"Royal Observatory" andCoordinate:twoLocation initWithDesc:@"Description about Cutty Sark"];
    [self.mapView addAnnotation:newAnnotation];
    [newAnnotation release];

    // Add Royal Naval College annotation to MapView
    newAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"Royal Naval College" andCoordinate:threeLocation initWithDesc:@"Description about Cutty Sark"];
    [self.mapView addAnnotation:newAnnotation];
    [newAnnotation release];

    // Add Queen's House annotation to MapView
    newAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"Queen's House" andCoordinate:fourLocation initWithDesc:@"Description about Cutty Sark"];
    [self.mapView addAnnotation:newAnnotation];
    [newAnnotation release];

    // Add National Maritime Museum annotation to MapView
    newAnnotation = [[MapViewAnnotation alloc] initWithTitle:@"National Maritime Museum" andCoordinate:fiveLocation initWithDesc:@"Description about Cutty Sark"];
    [self.mapView addAnnotation:newAnnotation];
    [newAnnotation release];


}

- (void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)anView
{
    AVSpeechSynthesizer *synthesizer = [[AVSpeechSynthesizer alloc]init];
    AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:((MapViewAnnotation *)anView).desc];
    [utterance setRate:0.5];
    [synthesizer speakUtterance:utterance];
}


// When a map annotation point is added, zoom to it (1500 range)
- (void)mapView:(MKMapView *)mv didAddAnnotationViews:(NSArray *)views
{
    MKAnnotationView *annotationView = [views objectAtIndex:0];
    id <MKAnnotation> mp = [annotationView annotation];
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance([mp coordinate], 1500, 1500);
    [mv setRegion:region animated:YES];
    //[mv selectAnnotation:mp animated:YES];

}

Any help would be appreciated!

EDIT Here is the NSLog:

Answer 1

In the didSelectAnnotationView delegate method, the anView parameter is the MKAnnotationView.

That is, anView is the view (MKAnnotationView or MKPinAnnotationView class) object of the annotation.

It is not the model (your MapViewAnnotation class) object of the annotation.

To refer to the annotation model instance that the view is for, use the view's annotation property and cast it to your class:

- (void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)anView
{
    //Get a reference to the annotation this view is for...
    id<MKAnnotation> annSelected = anView.annotation;

    //Before casting, make sure this annotation is our custom type
    //(and not some other type like MKUserLocation)...
    if ([annSelected isKindOfClass:[MapViewAnnotation class]])
    {
        MapViewAnnotation *mva = (MapViewAnnotation *)annSelected;

        AVSpeechSynthesizer *synthesizer = [[AVSpeechSynthesizer alloc]init];

        AVSpeechUtterance *utterance = 
            [AVSpeechUtterance speechUtteranceWithString:mva.desc];

        [utterance setRate:0.5];
        [synthesizer speakUtterance:utterance];
    }
}