如何使自定义MKAnnotation可拖动

Question

我需要具有不同引脚图像的MKAnnotation.
所以我创建了以下:

@interface NavigationAnnotation : NSObject <MKAnnotation>
- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate;
...
@interface NavigationAnnotation ()
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *address;
@property (nonatomic, assign) CLLocationCoordinate2D theCoordinate;
@end

@implementation NavigationAnnotation


- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate {
    if ((self = [super init])) {
        if ([name isKindOfClass:[NSString class]]) {
            self.name = name;
        } else {
            self.name = @"Unknown charge";
        }
        self.address = address;
        self.theCoordinate = coordinate;
    }
    return self;
}

- (NSString *)title {
    return _name;
}

- (NSString *)subtitle {
    return _address;
}

- (CLLocationCoordinate2D)coordinate {
    return _theCoordinate;
}

并添加如下:

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation{

    static NSString *identifier_OrderAnnotation = @"NavigateAnnotation";

    if ([annotation isKindOfClass:[MKUserLocation class]])
        return nil;

    if ([annotation isKindOfClass:[NavigationAnnotation class]]) {

        MKAnnotationView *annotationView = (MKAnnotationView *) [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier_OrderAnnotation];
        if (annotationView == nil) {
            annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier_OrderAnnotation];
            annotationView.enabled = YES;
            annotationView.canShowCallout = YES;
            annotationView.draggable = YES;
            annotationView.image = [UIImage imageNamed:@"myimage.png"];
        } else {
            annotationView.annotation = annotation;
        }

        return annotationView;
    }
}

注释显示在地图上很好,但由于某种原因它不可拖动:(

Answer 1

如前所述,对于可拖动的注释,它必须实现一个setCoordinate:方法.

此外,从iOS 7开始,您可能还需要实现该mapView:annotationView:didChangeDragState:方法(请参阅Draggable Pin在地图上没有固定位置,并且iOS MapKit拖动注释(MKAnnotationView)不再平移地图).

您可以setCoordinate:自己显式实现该方法,也可以只声明一个可写coordinate属性(命名完全相同)并合成它(并且将自动为您实现getter和setter方法).

(请注意,如果使用预定义的MKPointAnnotation类,则不需要执行此操作,因为该类已实现可设置的coordinate属性.)

在你的NavigationAnnotation班级,实行明确的,手动解决方案与现有的工作theCoordinate性质,只是添加的setCoordinate:方法,以你的类实现(保持现有的getter方法):

-(void)setCoordinate:(CLLocationCoordinate2D)newCoordinate
{
    self.theCoordinate = newCoordinate;
}

您可能还需要在实现didChangeDragState:地图视图委托的类中实现该方法(具有该viewForAnnotation方法的同一个),否则在拖动之后,注释视图将在地图上方就地悬停,即使在其下方进行平移或缩放时也是如此.Chris K.在他的回答中给出的方法的示例实现:

- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)annotationView didChangeDragState:(MKAnnotationViewDragState)newState fromOldState:(MKAnnotationViewDragState)oldState
{
    if (newState == MKAnnotationViewDragStateStarting)
    {
        annotationView.dragState = MKAnnotationViewDragStateDragging;
    }
    else if (newState == MKAnnotationViewDragStateEnding || newState == MKAnnotationViewDragStateCanceling)
    {
        annotationView.dragState = MKAnnotationViewDragStateNone;
    }
}