ios - 根据所选的MKAnnotationView动态更改leftCalloutAccessoryView

我有一组图像，这些图像与 map 上的每个Annotation相关联。我可以将图片静态添加到leftCalloutAccessoryView中，但不确定如何使它动态化。我希望清楚我的要求。每个注释都有自己想要显示的图像，但是我不确定如何通过以下方法引用该图像；

- (MKAnnotationView *)mapView:(MKMapView *)mv viewForAnnotation:(id <MKAnnotation>)annotation
{
    if([annotation isKindOfClass:[MKUserLocation class]])
    return nil;

    NSString *annotationIdentifier = @"PinViewAnnotation";

    MyAnnotationView *pinView = (MyAnnotationView *) [mv dequeueReusableAnnotationViewWithIdentifier:annotationIdentifier];


    if (!pinView)
    {
        pinView = [[MyAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotationIdentifier];

       pinView.canShowCallout = YES;

       UIImageView *houseIconView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Icon"]];//static image
        [houseIconView setFrame:CGRectMake(0, 0, 30, 30)];
        pinView.leftCalloutAccessoryView = houseIconView;

    }
    else
    {
        pinView.annotation = annotation;
    }

    return pinView;

}

我的数组“self.sandwiches”包含具有名称(Sandwich)和imageName('NSString')的NSString对象。

我正在寻找一种解决方案，可以获取所选引脚的索引，类似于UITableView，您可以获取其索引，并使用indexPath.row从数组访问它。

我的注释课；
。H
＃进口
＃进口
＃进口

@interface SandwichAnnotation : NSObject<MKAnnotation>
@property (nonatomic,assign) CLLocationCoordinate2D coordinate;
@property (nonatomic,copy) NSString * title;
@property (nonatomic,copy) NSString * subtitle;

@end

#import "SandwichAnnotation.h"

@implementation SandwichAnnotation
@synthesize coordinate,title,subtitle;

@end

最佳答案

在viewForAnnotation中，我建议将所需的数据添加到注释类本身中，而不是“获取引脚的索引”(这可以工作，但效率不如UITableView)。

这样，数据将更加独立，并且无需担心，知道或与注释对象存储在何处或哪种结构保持同步，委托方法或其他地方的代码。您具有对注释对象的引用，您将立即拥有该注释所需的所有数据(或者至少它将在其内部包含对相关数据的引用)。
viewForAnnotation委托方法提供对其需要查看的注释对象的引用(annotation参数)。通常将其键入为id<MKAnnotation>，但实际上它是所创建的确切类型的实例(您自己创建的SandwichAnnotation或 map 视图中的MKUserLocation)。

一种选择是使父Sandwich类本身实现MKAnnotation并消除SandwichAnnotation类。这样，由于annotation参数实际上是Sandwich，因此根本不需要搜索或引用。

但是，您可能需要为注释对象保留一个单独的类(很好)。在这种情况下，您可以在注释类中添加对父对象的引用。例:

@interface SandwichAnnotation : NSObject<MKAnnotation>
@property (nonatomic,assign) CLLocationCoordinate2D coordinate;
@property (nonatomic,copy) NSString * title;
@property (nonatomic,copy) NSString * subtitle;
@property (nonatomic,retain) Sandwich * whichSandwich;  // <-- add reference
@end

创建SandwichAnnotation时，设置注释用于的Sandwich的引用:

for (Sandwich *currentSandwich in self.sandwiches) {
    SandwichAnnotation *sa = [[SandwichAnnotation alloc] init...];
    sa.coordinate = ...
    sa.title = ...
    sa.whichSandwich = currentSandwich; // <-- set reference

    [mapView addAnnotation:sa];
}

最后，在viewForAnnotation中，如果annotation类型为SandwichAnnotation，则设置leftCalloutAccessoryView:

- (MKAnnotationView *)mapView:(MKMapView *)mv viewForAnnotation:(id <MKAnnotation>)annotation
{
    if (! [annotation isKindOfClass:[SandwichAnnotation class]]) {
        //If annotation is not a SandwichAnnotation, return default view...
        //This includes MKUserLocation.
        return nil;
    }

    //At this point, we know annotation is of type SandwichAnnotation.
    //Cast it to that type so we can get at the custom properties.
    SandwichAnnotation *sa = (SandwichAnnotation *)annotation;

    NSString *annotationIdentifier = @"PinViewAnnotation";

    MyAnnotationView *pinView = (MyAnnotationView *) [mv dequeueReusableAnnotationViewWithIdentifier:annotationIdentifier];


    if (!pinView)
    {
        pinView = [[MyAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotationIdentifier];

       pinView.canShowCallout = YES;

       //Here, just initialize a blank UIImageView ready to use.
       //Set image below AFTER we have a dequeued or new view ready.
       UIImageView *houseIconView = [[UIImageView alloc] init];
       [houseIconView setFrame:CGRectMake(0, 0, 30, 30)];
       pinView.leftCalloutAccessoryView = houseIconView;
    }
    else
    {
        pinView.annotation = annotation;
    }

    //At this point, we have a dequeued or new view ready to use
    //and pointing to the correct annotation.
    //Update image on the leftCalloutAccessoryView here
    //(not just when creating the view otherwise an annotation
    //that gets a dequeued view will show an image of another annotation).

    UIImageView *houseIconView = (UIImageView *)pinView.leftCalloutAccessoryView;
    NSString *saImageName = sa.whichSandwich.imageName;
    UIImage *houseIcon = [UIImage imageNamed: saImageName];

    if (houseIcon == nil) {
        //In case the image was not found,
        //set houseIcon to some default image.
        houseIcon = someDefaultImage;
    }

    houseIconView.image = houseIcon;

    return pinView;

}

关于ios - 根据所选的MKAnnotationView动态更改leftCalloutAccessoryView，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/25248405/