DetailDisclosure按钮未在注释视图中显示 [英] DetailDisclosure button not showing in annotation view

问题描述

出于某种奇怪的原因，详细信息按钮以某种方式停止出现:

For some odd reason the detail button somehow stopped appearing:

- (MKAnnotationView *)mapView:(MKMapView *)mV viewForAnnotation:(id <MKAnnotation>)annotation
{
MKPinAnnotationView *pinAnnotation = nil;
if(annotation != mapView.userLocation) 
{
    MKPinAnnotationView *pinAnnotation = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:@"sadasdasd"];
    if ( pinAnnotation == nil ){
        pinAnnotation = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"sadasdasd"] autorelease];

        /* add detail button */
        NSLog(@"Here");

        UIButton *infoButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
        pinAnnotation.rightCalloutAccessoryView = infoButton;


    }

}

return pinAnnotation;
}

此处输出. 提前致谢.

Here is output. Thanks in advance.

推荐答案

第一个问题是pinAnnotation在该方法中声明了两次.

First problem is that pinAnnotation is declared twice in that method.

在if(annotation != mapView.userLocation)...块的第一行和第二行中一次.因此，由于从未设置外部变量(导致没有附件的默认MKAnnotationView标注)，所以return语句返回nil.

Once in the first line and second in the if(annotation != mapView.userLocation)... block. Because of this, the return statement returns nil because the outer variable is never set (resulting in a default MKAnnotationView callout with no accessory).

将第二个声明更改为仅一个赋值.

Change the second declaration to just an assignment.

下一个问题是您需要将canShowCallout设置为YES，因为MKPinAnnotationView的默认值为NO.您可以在设置附件视图后执行以下操作:

Next problem is that you need to set canShowCallout to YES because the default is NO for an MKPinAnnotationView. You can do this after setting the accessory view:

pinAnnotation.canShowCallout = YES;

以上内容应解决附件按钮未显示的问题.

The above should fix the accessory button not showing.

无关，但是在重用视图时，还需要设置视图的annotation属性(在出队后不为nil的情况下).因此，将else块添加到if (pinAnnotation == nil):

Unrelated, but you also need to set the view's annotation property when it is being re-used (in the case when it is not nil after the dequeue). So add an else block to the if (pinAnnotation == nil):

else {
    //annotation view being re-used, set annotation to current...
    pinAnnotation.annotation = annotation;
}

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