为什么我无法设置注释地址的图钉地址？

Question

Trying to set address of pin position to annotation subtitle if it == nil. But nothing happens.

if (myAnnotation.subtitle == nil)
                    [self.geoCoder reverseGeocodeLocation: locationManager.location completionHandler: 
                     ^(NSArray *placemarks, NSError *error) {

                         CLPlacemark *placemark = [placemarks objectAtIndex:0];
                         NSString *locatedAt = [[placemark.addressDictionary valueForKey:@"FormattedAddressLines"] componentsJoinedByString:@", "];  
                         myAnnotation.subtitle = locatedAt;

                     }];   
                else {
                    myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
                }

Answer 1

The thing that is going on with your code is that the geocoder is an asynchronous operation. Your pins are being placed before the completion of the geocode. Depending on how your code is set up you may be losing the reference to your pin before the geocode is complete. Try geocoding your placemark before you create the annotations.