MapView Problems - Pin change color when map reloded - xcode

Question

I have a problem with the PIn color mapView when a refresh is done.
In my I app i display some point with two color in order to identify if a service is available.
On the first start, no problems appear. The code is the follower:
- (void)viewDidLoad
{
[super viewDidLoad];
[self dowloadPoint]; // here I exucte the first start
}
- (void)dowloadPoint{
NSURL *url1 =[NSURL URLWithString:#"http:MYUSRL"];
NSData *datos1 =[[NSData alloc] initWithContentsOfURL:url1];
[self plotBarPosition:datos_string1]; //Here I call the plotBarPosition method
}
- (void)plotBarPosition:(NSString *)datos_string1 {
for (id<MKAnnotation> annotation in _mapView.annotations) {
[_mapView removeAnnotation:annotation];
}
// Parse the string into JSON
NSDictionary *json = [(NSDictionary*)[datos_string1 JSONValue]objectForKey:#"features"];
// Get the objects you want, e.g. output the second item's client id
NSArray *items_properties = [json valueForKeyPath:#"properties"];
NSArray *items_geo = [json valueForKeyPath:#"geometry"];
for (int i = 0; i < [json count]; i++){
NSString *nomprePunto =[[items_properties objectAtIndex:i] objectForKey:#"title"];
NSNumber *lat =[[[items_geo objectAtIndex:i] objectForKey:#"coordinates"] objectAtIndex:0];
NSNumber *lon =[[[items_geo objectAtIndex:i] objectForKey:#"coordinates"] objectAtIndex:1];
CLLocationCoordinate2D coordinate;
coordinate.latitude = lat.doubleValue;
coordinate.longitude = lon.doubleValue;
//ESTADO
NSString *description = [[items_properties objectAtIndex:i] objectForKey:#"description"];
NSString *estado_punto = [[NSString alloc]init];
if ([description rangeOfString:#"Averiado"].location == NSNotFound) {
estado_punto = #"Available";
} else {
estado_punto = #"NOt Available";
averiados ++;
}
NSString *averiadosStr = [NSString stringWithFormat:#"%d",averiados];
averiadosLabel.text = averiadosStr;
MyLocation *location =[[MyLocation alloc] initWithName:nomprePunto coordinate:coordinate estado:estado_punto];
[_mapView addAnnotation:location];
}
}
- (MKPinAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(MyLocation *)annotation {
static NSString *identifier = #"MyLocation";
if ([annotation isKindOfClass:[MyLocation class]]) {
MKPinAnnotationView *annotationView = (MKPinAnnotationView *) [_mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if (annotationView == nil) {
annotationView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
if([[annotation estado] isEqualToString:#"En Servicio"])
annotationView.pinColor = MKPinAnnotationColorGreen;
} else {
annotationView.annotation = annotation;
}
return annotationView;
}
return nil;
}
But whe I add a refres button that is function is simply a refreshcalling the dowloadPoint once again,
- (IBAction)refresh{
[self dowloadPoint];
}
the color of pins change in a "random manner", not corrisponding with the real state of point.
Any ideas about what is happening? Thanks in advance.
EDIT: It seemps pproblems is due to:
for (id<MKAnnotation> annotation in _mapView.annotations) {
[_mapView removeAnnotation:annotation];
}
erasing it, the app work properly but pins area drown abow the previous ones...:S

Answer 1

The default color of the pin is red. You set it to green if the estado property of your MyLocation object is equal to #"En Servicio". I understand that sometimes the color is red, when your estado property is equal to #"En Servicio", or sometimes green when it is not.
One reason could be that your MyLocation object simply does no longer exist when you press the refresh button. In this case, you might still have a pointer to the memory location where it once existed, but this location may have been overwritten by anything, causing a random color.
This can happen e.g. if your MyLocation object has been created as an autorelease object that has been released when you returned to the main event loop, i.e. to handle user interactions.
This should not be the case if you are using ARC.