MKPointAnnotation不再在iOS 11中显示标题

Question

我在iOS 10中用于显示注释和标题的代码，不再在iOS 11中显示标题。在iOS 11中，选择了注释，但标题不再显示。有关获得标题的提示，就像在iOS 10中一样吗？

MKPointAnnotation* theAnnotation = [MKPointAnnotation new];
theAnnotation.coordinate = CLLocationCoordinate2DMake( aLocation.latDegrees, aLocation.lonDegrees );
[theAnnotation setTitle:@"Hello world"];

[self.mapView removeAnnotations:self.mapView.annotations];
[self.mapView addAnnotation:theAnnotation];
[self.mapView showAnnotations:@[theAnnotation] animated:NO];
[self.mapView selectAnnotation:theAnnotation animated:YES];

Answer 1

您应该实现此委托方法：

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
    static NSString* Identifier = @"PinAnnotationIdentifier";
    MKPinAnnotationView* pinView;
    pinView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:Identifier];

    if (pinView == nil) {
        pinView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation
                                                  reuseIdentifier:Identifier];
        pinView.canShowCallout = YES;
        return pinView;
    }
    pinView.annotation = annotation;
    return pinView;
}

iOS 11上的结果