Search code examples
iphoneobjective-cmkannotation

MKAnnotation, simple example


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?


Solution

  • 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.