MKAnnotation, simple example

Question

Is there a simple example project for MKAnnotation? I don't know what to pass at "addAnnotation", as it wants some "id<Annotation>". The examples at the developer site are all with arrays or parsers or so, I just need a very easy example to first understand, how the whole thing works.

Thanks in advance..

EDIT:

I set up a class Pin. In the .h it writes

#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>

@interface Pin : NSObject <MKAnnotation> {
CLLocationCoordinate2D coordinate;
NSString *title;
NSString *subTitle;
}

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

- (id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:(NSString *)placeName description:(NSString *)description;
@end

according to what onnoweb answered.

In the Pin.m, I implemented like this, according to different examples:

#import "Pin.h"

@implementation Pin

@synthesize title, subTitle;

- (CLLocationCoordinate2D) coordinate {
CLLocationCoordinate2D coords;
coords.latitude = coordinate.latitude; //i want it that way
coords.longitude =  7.1352260; //this way it works

return coords;

- (NSString *) title {
return @"Thats the title";
}

- (NSString *) subtitle {
return @"Thats the sub";
}

- (id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:(NSString *)placeName description:(NSString *)description {

return self;
}

- (void) dealloc {
[super dealloc];
}

@end

So if I set the coordinates by hand, as pointed in the comment, it works. But I'd like to be able to set the value dynamically like in the first comment. I tried various ways, but none worked out. As you don't specify a - (CLLocationCoordinate2D) coordinate I tried to just synthesize coordinate, but like that it won't work either.

Could you show me your MapPin.m?

EDIT 2:

I set mapCenter like

- (void)viewWillAppear:(BOOL)animated {
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.delegate = self;
[self.locationManager startUpdatingLocation];

CLLocation *curPos = locationManager.location;
location = curPos.coordinate;

CLLocationCoordinate2D mapCenter;
mapCenter.latitude =  location.latitude;
mapCenter.longitude = location.longitude;

MKCoordinateSpan mapSpan;
mapSpan.latitudeDelta = 0.005;
mapSpan.longitudeDelta = 0.005;

MKCoordinateRegion mapRegion;
mapRegion.center = mapCenter;
mapRegion.span = mapSpan;

mapKitView.region = mapRegion;
mapKitView.mapType = MKMapTypeStandard;
mapKitView.showsUserLocation=TRUE;
}

Anything wrong with that?

Answer 1

You need to have a class implementing the MKAnnotation protocol. Here is a snippet from one of my projects:

@interface MapPin : NSObject<MKAnnotation> {
    CLLocationCoordinate2D coordinate;
    NSString *title;
    NSString *subtitle;
}

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

- (id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:(NSString *)placeName description:(NSString *)description;

@end

Then, where you create the map you'll call:

pin = [[MapPin alloc] initWithCoordinates:[track startCoordinates] placeName:@"Start" description:@""];
[map addAnnotation:pin];

EDIT:

Here is the implementation:

@implementation MapPin

@synthesize coordinate;
@synthesize title;
@synthesize subtitle;

- (id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:placeName description:description {
    self = [super init];
    if (self != nil) {
        coordinate = location;
        title = placeName;
        [title retain];
        subtitle = description;
        [subtitle retain];
    }
    return self;
}

- (void)dealloc {
    [title release];
    [subtitle release];
    [super dealloc];
}


@end

Hope this helps, Onno.