iOS:为什么我不能让 mapkit 显示自定义注释图钉图像? [英] iOS : Why can't I get mapkit to display a custom annotation pin image?

问题描述

认为使用我自己的自定义图钉图像进行注释会非常容易.

figured that using my own custom pin image for annotations would be super easy.

但我一直无法让它工作，我不知道为什么！

But I have never been able to get it to work, and I have no idea why!

我只是在使用:

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

    NSString *annotationIdentifier = @"CustomViewAnnotation";
    CustomAnnotationView * customAnnotationView = (CustomAnnotationView *) [self.mapview dequeueReusableAnnotationViewWithIdentifier:annotationIdentifier];
    if(!customAnnotationView)
    {
        customAnnotationView=[[CustomAnnotationView alloc] initWithAnnotationWithImage:annotation
                                                                       reuseIdentifier:annotationIdentifier 
                                                                   annotationViewImage:[UIImage imageNamed:@"map_location_pin.png"]];
    }

    customAnnotationView.image=[UIImage imageNamed:@"map_location_pin.png"];

    customAnnotationView.canShowCallout= YES;

    return customAnnotationView;
}

我认为这应该可行，因为 UIImage 正是它想要的，而且我的项目中确实有 .png 文件.

I assumed that this should work, as a UIImage is what it is wanting, and I do have the .png file in my project.

它从不使用我的图像，而只是使用标准的红色图钉.我在这里做错了什么?

It never uses my image, but just the standard red pin. What am I doing wrong here?

推荐答案

一些想法:

1. 您是否为 MKMapView 定义了 delegate?您是否在此处放置了断点或 NSLog 以确保您的 viewForAnnotation 被调用?

1. Did you define your delegate for your MKMapView? Have you put a breakpoint or NSLog in here to make sure your viewForAnnotation is getting called?

你还没有分享你的 CustomAnnotationView 接口/实现细节，但你不需要子类化 MKAnnotationView 除非你在那里做一些特别的事情.如果你只是替换图像，你可以这样做:

You haven't shared your CustomAnnotationView interface/implementation details, but you don't need to subclass MKAnnotationView unless you're doing something special in there. If you're just replacing the image, you can just do:

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

    NSString *annotationIdentifier = @"CustomViewAnnotation";
    MKAnnotationView* annotationView = [mapview dequeueReusableAnnotationViewWithIdentifier:annotationIdentifier];

    if (annotationView) {
        annotationView.annotation = annotation;
    } else {
        annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotationIdentifier];
    }

    annotationView.image = [UIImage imageNamed:@"map_location_pin.png"];
    annotationView.canShowCallout= YES;

    return annotationView;
}

显然，如果您正在做一些有趣的事情(例如拖放引脚时的自定义注释)，请继续使用您的 CustomAnnotationView 子类 MKAnnotationView.这取决于你想要做什么.

Clearly, though, if you're doing something interesting (like custom annotation when a pin is dragged or dropped), then go ahead and have your CustomAnnotationView subclass MKAnnotationView. It just depends upon what you're trying to do.

与您最初的问题无关，我建议:

Unrelated to your original question, I'd suggest:

• 您的 viewForAnnotation 方法仅使用本地 mapView 变量而不是引用类属性 self.mapView(尽管它们'毫无疑问是一样的)，

• that your viewForAnnotation method just use the local mapView variable rather than referencing a class property, self.mapView (though they're undoubtedly the same),

您考虑重命名自定义 init 方法.所以，而不是:

that you contemplate renaming your custom init method. So instead of:

customAnnotationView = [[CustomAnnotationView alloc] initWithAnnotationWithImage:annotation
                                                                 reuseIdentifier:annotationIdentifier 
                                                             annotationViewImage:[UIImage imageNamed:@"map_location_pin.png"]];

你会做这样的事情:

customAnnotationView = [[CustomAnnotationView alloc] initWithAnnotation:annotation
                                                        reuseIdentifier:annotationIdentifier 
                                                                  image:[UIImage imageNamed:@"map_location_pin.png"]];

如果您仍然遇到问题，请与我们分享您的一些 CustomAnnotationView 代码.

If you're still having troubles, share some of your CustomAnnotationView code with us.

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