title: Problems with MapView Pin Annotation - Pin loses color when map is zoomed/panned/region changes
body: <p>I have a mapview that displays locations of cash points. Annotations are dropped and the callout can be clicked on to go to a page with more detail about that location. There are two categories of cashpoint, free and paid, free cashpoint pins are green and the other red. When the pins drop they are the correct colours. Everything works fine untill i zoom to user location or other areas of the map then when i go back to the pins they have lost their colour formatting and are all the original red colour.</p>
  
  <p>I assume this is something to do with the map reloading when it downloads tiles and not reloading the pins properly, although i could be wrong.</p>
  
  <p>Any help will be much appreciated.</p>
  
  <p>here is my code:</p>
  
  <pre><code>#import "CashPointMapViewController.h"
  #import "PinDrop.h"
  #import "CashPointDetailViewController.h"
  
  @implementation CashPointMapViewController
  @synthesize app, theCashList, mapview, ann, count, myArray, pinColor;
  
  - (IBAction) getlocation { 
  
      MKCoordinateRegion region;
      region.center = self.mapview.userLocation.coordinate;
      region.span.longitudeDelta = 0.01f;
      region.span.longitudeDelta = 0.01f;
      [mapview setRegion:region animated:YES];
  }
  
  - (void)viewDidLoad {
  
      [super viewDidLoad];
  
      mapview.showsUserLocation = YES;
  
      [mapview setMapType:MKMapTypeStandard];
      [mapview setZoomEnabled:YES];
      [mapview setScrollEnabled:YES];
  
      MKCoordinateRegion region = { {0.0, 0.0 }, {0.0, 0.0 } };
      region.center.latitude = 53.801279;
      region.center.longitude = -1.548567;
      region.span.longitudeDelta = 0.3f;
      region.span.longitudeDelta = 0.3f;
      [mapview setRegion:region animated:YES];
  
      app = [[UIApplication sharedApplication]delegate];
  
      UIImage *locate = [UIImage imageNamed:@"location arrow white.png"];
  
      UIBarButtonItem *userlocatebutton = [[UIBarButtonItem alloc] initWithImage:locate     style:UIBarButtonItemStylePlain target:self action:@selector(getlocation)];
  
      self.navigationItem.rightBarButtonItem = userlocatebutton;
  
      [self performSelectorInBackground:@selector(annloop) withObject:self];
  
  }
  
  
  -(void) annloop {
  
      int i;
      for (i=0; i&lt;=count-1; i = i+1) {
      theCashList = [myArray objectAtIndex:i];
  
      NSString *trimlat = [theCashList.lat stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
      NSString *trimlon = [theCashList.lon stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
  
      double latdouble = [trimlat doubleValue];
      double londouble = [trimlon doubleValue];
  
      CLLocationCoordinate2D coord = {(latdouble),(londouble)};
  
      ann = [[PinDrop alloc] init];
  
      ann.index = i;
  
      ann.title = [theCashList.name stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
  
      NSString *street = [theCashList.street stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
      NSString *town = [theCashList.town stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
      NSString *postcode = [theCashList.postcode stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
  
      NSString *address = [[NSString alloc] initWithFormat:@"%@, %@, %@", street, town, postcode];
  
      ann.subtitle = address;
      ann.coordinate = coord;
  
      NSString *trimprice = [theCashList.price stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
  
      if ([trimprice isEqualToString:@"Free"])
      {
          ann.price = 1;
      }
      else
      {
          ann.price = 0;
      }
      [mapview performSelectorOnMainThread:@selector(addAnnotation:) withObject:ann waitUntilDone:YES];
      }
  }
  
  
  -(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id&lt;MKAnnotation&gt;)annotation {
  
      if ([annotation isKindOfClass:[MKUserLocation class]])
      return nil;
  
      MKPinAnnotationView *mypin = [[MKPinAnnotationView alloc]initWithAnnotation:ann reuseIdentifier:@"current"];
      mypin.backgroundColor = [UIColor clearColor];
      UIButton *goToDetail = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
      mypin.rightCalloutAccessoryView = goToDetail;
      mypin.draggable = NO;
      mypin.animatesDrop = TRUE;
      mypin.canShowCallout = YES;
  
  
      if (ann.price == 1)
      {
          mypin.pinColor = MKPinAnnotationColorGreen;
      }
      else
      {
          mypin.pinColor = MKPinAnnotationColorRed;
      }
      return mypin;
      }
  
  
  - (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view
  calloutAccessoryControlTapped:(UIControl *)control {
  
     PinDrop *annView = view.annotation;
      CashPointDetailViewController *detailView = [[CashPointDetailViewController alloc]init];
      theCashList = [myArray objectAtIndex:annView.index];
      detailView.theCashList = theCashList;
      [self.navigationController pushViewController:detailView animated:YES];
  
  }
  
  
  - (void)viewDidUnload {
  
      [super viewDidUnload];
  }
  
  - (BOOL)shouldAutorotateToInterfaceOrientation:   (UIInterfaceOrientation)interfaceOrientation {
      return (interfaceOrientation == UIInterfaceOrientationPortrait);
  }
  
  @end
  </code></pre>
  
  <p>EDIT: Here is my .h if it helps.</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  #import "AppDelegate.h"
  #import "CashPointList.h"
  #import &lt;MapKit/MapKit.h&gt;
  #import "PinDrop.h"
  
  @interface CashPointMapViewController : UIViewController  {
  
      MKMapView *mapview;
      PinDrop *ann;
  }
  
      @property (nonatomic, retain) AppDelegate *app;
      @property (nonatomic, retain) CashPointList *theCashList;
      @property (nonatomic, retain) PinDrop *ann;
      @property (nonatomic, retain) IBOutlet MKMapView *mapview;
      @property (nonatomic, readwrite) int count;
      @property (nonatomic, retain) NSMutableArray *myArray;
      @property (nonatomic) MKPinAnnotationColor pinColor;
  
      -(IBAction) getlocation;
  
  
  @end
  </code></pre>