问题描述
我有一个 Picture
类,它包含每个位置的 latitude
和 longitude
和 image
.我想将它们作为注释添加到 MapView
并显示其图像而不是这些位置的图钉.
I have a class of Picture
which contains latitude
and longitude
and image
of each location. I want to add them as annotation to the MapView
and show its image instead of pin for those locations.
我有一个自定义的注释:
I have a customized annotation which is:
@interface Annotation : MKAnnotationView <MKAnnotation>
@property (nonatomic,assign) CLLocationCoordinate2D coordinate;
@property (nonatomic,copy) NSString *title;
@property (nonatomic,copy) NSString *subtitle;
@property (nonatomic,retain) UIImage *image;
@end
和
@implementation Annotation
@synthesize title,subtitle,coordinate,image;
@end
现在在主代码中我正在尝试这个:
Now in main code I am trying this:
CLLocationCoordinate2D location;
Annotation *myAnn;
for(Pictures *pic in picturesFromDB)
{
myAnn = [[Annotation alloc] init];
location.latitude = [pic.langT doubleValue];
location.longitude = [pic.longT doubleValue];
myAnn.coordinate = location;
myAnn.title = pic.descript;
myAnn.image = [UIImage imageWithData:pic.image]; //Not sure about this line!
[self.mapView addAnnotation:myAnn];
}
我是否仍然需要委托并且必须调用viewForAnnotation"?因为它不起作用,我为委托做了这个:
Do I still need the delegate and must call "viewForAnnotation"? Because it did not work, I did this for delegate:
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
// If it's the user location, just return nil.
if ([annotation isKindOfClass:[MKUserLocation class]])
return nil;
// Handle any custom annotations.
if ([annotation isKindOfClass:[Annotation class]])
{
// Try to dequeue an existing pin view first.
MKAnnotationView *pinView = (MKAnnotationView*)[mapView dequeueReusableAnnotationViewWithIdentifier:@"CustomPinAnnotationView"];
if (!pinView)
{
// If an existing pin view was not available, create one.
pinView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"CustomPinAnnotationView"];
//pinView.animatesDrop = YES;
pinView.canShowCallout = YES;
pinView.image = [UIImage imageNamed:@"image.png"];
pinView.calloutOffset = CGPointMake(0, 4);
} else {
pinView.annotation = annotation;
}
return pinView;
}
return nil;
}
这工作正常,但向所有位置添加了相同的图像.但是我有一个特定的图像要显示,而不是为每个位置显示上面的 image.png
.
This is working fine but adding same image to all the locations. But I have a specific image to show instead of image.png
above for each location.
位置的数量是可变的,也是动态的.
Number of location is variable and also dynamic.
如何将图像传递给委托.我试图在传递的注释中找到图像字段,但它不存在!我感谢任何建议.
How can I pass that image to the delegate. I tried to find the image field in the passed annotation, but it does not exist! I appreciate any suggestion.
推荐答案
您需要将注解强制转换为您的自定义类,以便您可以访问其属性 -
You need to cast the annotation to your custom class so that you can access its properties -
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
// Handle any custom annotations.
if ([annotation isKindOfClass:[Annotation class]])
{
Annotation *myAnn=(Annotation *)annotation;
// Try to dequeue an existing pin view first.
MKAnnotationView *pinView = (MKAnnotationView*)[mapView dequeueReusableAnnotationViewWithIdentifier:@"CustomPinAnnotationView"];
if (!pinView)
{
// If an existing pin view was not available, create one.
pinView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"CustomPinAnnotationView"];
//pinView.animatesDrop = YES;
pinView.canShowCallout = YES;
pinView.calloutOffset = CGPointMake(0, 4);
} else {
pinView.annotation = annotation;
}
pinView.image = myAnn.image;
return pinView;
}
return nil;
}
这篇关于如何为 MapView 上的每个自定义注释添加图像?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!