我实现了一个自定义注释(ContainerAnnotation),它派生自MKAnnotation,以及一个带有drawRect:方法的自定义注释视图(ContainerAnnotationView),后者派生自MKAnnotationView。但是,我无法弄清楚为什么drawRect:方法没有被调用。
下面是我注释视图的源代码。
ContainerAnnotationView.h:
下面是我注释视图的源代码。
ContainerAnnotationView.h:
@interface ContainerAnnotationView : MKAnnotationView
{
}
@end
ContainerAnnotationView.m:
@implementation ContainerAnnotationView
- (void) drawRect: (CGRect) rect
{
// Draw the background image.
UIImage * backgroundImage = [UIImage imageNamed: @"container_flag_large.png"];
CGRect annotationRectangle = CGRectMake(0.0f, 0.0f, backgroundImage.size.width, backgroundImage.size.height);
[backgroundImage drawInRect: annotationRectangle];
// Draw the number of annotations.
[[UIColor whiteColor] set];
UIFont * font = [UIFont systemFontOfSize: [UIFont smallSystemFontSize]];
CGPoint point = CGPointMake(2, 1);
ContainerAnnotation * containerAnnotation = (ContainerAnnotation *) [self annotation];
NSString * text = [NSString stringWithFormat: @"%d", containerAnnotation.annotations.count];
[text drawAtPoint: point withFont: font];
}
@end
从我的视图控制器中:
- (MKAnnotationView *) mapView: (MKMapView *) mapView viewForAnnotation: (id <MKAnnotation>) annotation
{
if ([annotation isKindOfClass: [ContainerAnnotation class]])
{
ContainerAnnotationView * annotationView = (ContainerAnnotationView *)[_mapView dequeueReusableAnnotationViewWithIdentifier: _containerMapAnnotationId];
if (annotationView == nil)
{
annotationView = [[[ContainerAnnotationView alloc] initWithAnnotation: annotation reuseIdentifier: _containerMapAnnotationId] autorelease];
annotationView.centerOffset = CGPointMake(0, -17.5);
annotationView.rightCalloutAccessoryView = [UIButton buttonWithType: UIButtonTypeDetailDisclosure];
annotationView.canShowCallout = YES;
}
annotationView.annotation = annotation;
return annotationView;
}
// etc...
}
我有其他使用普通MKAnnotation和图像的注释,它们可以正常工作。我还有另一个自定义注释视图,它没有实现drawRect:,但也可以正常工作。你有什么想法,我在这里做错了什么?