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我在设置地标的标题和副标题时遇到问题。

CLGeocoder *geocoder = [[CLGeocoder alloc] init];
            [geocoder geocodeAddressString:location 
                 completionHandler:^(NSArray* placemarks, NSError* error){
                     if (placemarks && placemarks.count > 0) {
                         CLPlacemark *topResult = [placemarks objectAtIndex:0];
                         MKPlacemark *placemark = [[MKPlacemark alloc] initWithPlacemark:topResult];

                         placemark.title = @"Some Title";
                         placemark.subtitle = @"Some subtitle";

                         MKCoordinateRegion region = self.mapView.region;
                         region.center = placemark.region.center;
                         region.span.longitudeDelta /= 8.0;
                         region.span.latitudeDelta /= 8.0;

                         [self.mapView setRegion:region animated:YES];
                         [self.mapView addAnnotation:placemark];
                     }
                 }
             ];

placemark.title = @"Some Title";和placemark.subtitle = @"Some subtitle";

给我一个错误：

Assigning to property with 'readonly' attribute not allowed

为什么我不能在这里设置标题和副标题？

4

1 回答 1

7

以为我会唤醒这个线程并给你一个我想出的解决方案。

据我所知，由于固有分配，MKPlacemark 的标题/副标题是只读属性。但是，使用我找到的解决方案，您可以简单地将 MKPlacemark 传递给 MKPointAnnotation，如下所示：

CLPlacemark *topResult = [placemarks objectAtIndex:0];

// Create an MLPlacemark

MKPlacemark *placemark = [[MKPlacemark alloc] initWithPlacemark:topResult];

// Create an editable PointAnnotation, using placemark's coordinates, and set your own title/subtitle
MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
point.coordinate = placemark.coordinate;
point.title = @"Sample Location";
point.subtitle = @"Sample Subtitle";


// Set your region using placemark (not point)          
MKCoordinateRegion region = self.mapView.region;
region.center = placemark.region.center;
region.span.longitudeDelta /= 8.0;
region.span.latitudeDelta /= 8.0;

// Add point (not placemark) to the mapView                                              
[self.mapView setRegion:region animated:YES];
[self.mapView addAnnotation:point];

// Select the PointAnnotation programatically
[self.mapView selectAnnotation:point animated:NO];

请注意，final[self.mapView selectAnnotation:point animated:NO];是一种允许自动弹出地标的解决方法。但是，该animated:BOOL部分似乎仅适用NO于 iOS5 - 如果您遇到手动弹出点注释的问题，您可能需要实施一种解决方法，可以在此处找到： MKAnnotation not getting selected in iOS5

我相信您现在已经找到了自己的解决方案，但我希望这在某种程度上能够提供信息。

于 2012-07-06T20:05:30.530 回答