IOS: Adding image to custom MKAnnotationview

问题:

I want to add a custom image to my annotations in the map. And i have made the following custom MapAnnotationView:

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#import <CoreLocation/CoreLocation.h>
@class POI;

@interface MapAnnotation : MKAnnotationView <MKAnnotation >

@property (nonatomic) CGFloat lat; 
@property (nonatomic) CGFloat lon;
@property (nonatomic) CGFloat altitude; 
@property (nonatomic,  copy) NSString * title;
@property (nonatomic, copy) NSString * subtitle;
@property (nonatomic,retain) NSString *source;
@property (nonatomic,retain) UIImage  *image;

@end

@implementation MapAnnotation
@synthesize coordinate;
@synthesize lat=_lat,lon=_lon,altitude= _altitude;
@synthesize subtitle= _subtitle, title= _title, source=_source, image =_img;


- (CLLocationCoordinate2D)coordinate;{
    CLLocationCoordinate2D position;
    if (_lat != 0.0 && _lon != 0.0) {
        position.latitude = _lat;
        position.longitude = _lon;

    }else {
        position.latitude=0.0;
        position.longitude=0.0;
    }

    return position; 
}

@end

-(void) mapDataToMapAnnotations{

    NSMutableArray *toRemove = [NSMutableArray arrayWithCapacity:10];
    for (id annotation in _map.annotations)
        if (annotation != _map.userLocation)
            [toRemove addObject:annotation];
    [_map removeAnnotations:toRemove];

    [_data removeAllObjects];

    [_data addObjectsFromArray:[UDdelegate naturArray]];


    if(_data != nil){
        MapAnnotation * tmpPlace;
        //for(NSDictionary * poi in _data){


        for(POI* poi in _data){

            tmpPlace = [[MapAnnotation alloc]init];

            tmpPlace.title = [poi title];
            tmpPlace.lat = [poi lat];
            tmpPlace.lon = [poi lon];
            tmpPlace.subtitle = [poi dist];
            tmpPlace.image = [poi poiIcon];

            [self.map addAnnotation:tmpPlace];
            [_map setNeedsLayout];
        }
    }
}

The problem is that the pins is the standard redPin.... I am sure that the icons isn't null, have checked for that.

Thanks

回答1:

You have to serve the MapKit delegate method mapView:viewForAnnotation: with a custom view.

- (MKAnnotationView *)mapView:(MKMapView *)map viewForAnnotation:(id <MKAnnotation>)annotation
{
    static NSString *annotationViewReuseIdentifier = @"annotationViewReuseIdentifier";

    MKAnnotationView *annotationView = (MKAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:annotationViewReuseIdentifier];

    if (annotationView == nil)
    {
        annotationView = [[[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotationViewReuseIdentifier] autorelease];
    }

    annotationView.image = [UIImage imageNamed:@"pin_image.png"];
    annotationView.annotation = annotation;

    return annotationView;
}

To encapsulate more you should create a custom annotation view like you did and serve the delegate method above with your class.

I advise you to rename the MapAnnotation class because it is confusing. There are also Annotations in iOS which are the data holders for those annotation views. To solve this I would prefer to write the type of the inherited class, in this case MKAnnotationView at the end of your custom class. For example CustomPinAnnotationView.