iphone-MKMapView标注在iOS 4.1的iPhone 4上不显示

canShowCallout

YES

placeAnnotation.canShowCallout = YES;

// set up new points
for(int i = 0; i < [_locations count]; i++) {
    PPlace * place = [_locations objectAtIndex:i];
    PlaceAnnotation * placeAnnotation = [[PlaceAnnotation alloc] initWithPlace:place];
    // if annotation is for currently selected place
    placeAnnotation.isCurrent = i == currentIndexPath.row;
    [self.mapView addAnnotation:placeAnnotation];
    if (placeAnnotation.isCurrent) {
        [self.mapView selectAnnotation:placeAnnotation animated:YES];
        placeAnnotation.canShowCallout = YES;
    }
    [placeAnnotation release];
}

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation

- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views

[yourMapView selectAnnotation: yourAnnotation animated: YES];