objective c - GMMGeoTileImageData error with MapKit -

in viewcontroller use maps , load list of pins. when move map or zoom in or out it, app crashes , displays error:

[gmmgeotileimagedata isequaltostring:]: unrecognized selector sent instance 0x862d3b0 

this code of view controller:

    - (void)viewdidload     {          statoann = [[nsmutablestring alloc] initwithformat:@"false"];          //bottone annulla per tornare indietro         uibarbuttonitem *annullabutton = [[[uibarbuttonitem alloc] initwithtitle:@"annulla" style:uibarbuttonitemstyleplain target:self action:@selector(backview)] autorelease];         self.navigationitem.leftbarbuttonitem = annullabutton;           //inizializzo la mappa         mapview = [[mkmapview alloc] initwithframe:cgrectmake(0, 0, 320, 416)];         mapview.delegate = self;         mapview.maptype = mkmaptypestandard;         [self.view addsubview:mapview];          [self setgmaps:arrdata];          [super viewdidload];     }   /** inizializzo l'annotation del poi mappa **/ - (void) setgmaps:(nsmutablearray*)inputdata {       // setto la lat e lng      cllocationdegrees latitude;     cllocationdegrees longitude;     cllocationcoordinate2d poilocation;     arrann = [[nsmutablearray alloc] init];      for(int i=0; i<[inputdata count]; i++) {          //ricavo la lat e lng del pin         latitude  = [[[inputdata objectatindex:i] objectforkey:@"latitude"]  doublevalue];         longitude = [[[inputdata objectatindex:i] objectforkey:@"longitude"] doublevalue];          // setto la location del poi         poilocation.latitude = latitude;         poilocation.longitude = longitude;         //[[[cllocation alloc] initwithlatitude:latitude longitude:longitude] autorelease];          //setto il pin         annotation *ann = [[annotation alloc] initwithcoordinate:poilocation];         ann.title = [[inputdata objectatindex:i] objectforkey:@"label"];         [arrann addobject:ann];         [ann release];       }       if (nil != self.arrann) {          [self.mapview addannotations:arrann];         //self.ann = nil;         self.arrann = nil;     }  }  /** setto il pin nella mappa ***/ - (void)setcurrentlocation:(cllocation *)location {      mkcoordinateregion region = {{0.0f, 0.0f}, {0.0f, 0.0f}};      region.center = location.coordinate;      region.span.longitudedelta = 0.1f;     region.span.latitudedelta  = 0.1f;      [self.mapview setregion:region animated:yes];     [self.mapview regionthatfits:region]; }   - (mkannotationview *)mapview:(mkmapview *)mapviewtemp viewforannotation:(id <mkannotation>)annotation {      mkpinannotationview *view = nil; // return nil current user location          view = (mkpinannotationview *)[mapview dequeuereusableannotationviewwithidentifier:@"identifier"];          if (nil == view) {             view = [[[mkpinannotationview alloc] initwithannotation:annotation reuseidentifier:@"identifier"] autorelease];             view.rightcalloutaccessoryview = [uibutton buttonwithtype:uibuttontypedetaildisclosure];         }          [view setpincolor:mkpinannotationcolorpurple];         [view setcanshowcallout:yes];         [view setanimatesdrop:yes];      if (![statoann isequaltostring:@"true"]) {         cllocation *location = [[cllocation alloc] initwithlatitude:annotation.coordinate.latitude                                                           longitude:annotation.coordinate.longitude];         [self setcurrentlocation:location];         statoann = [nsmutablestring stringwithformat:@"true"];     }        return view; } 

in viewforannotation, line:

statoann = [nsmutablestring stringwithformat:@"true"]; 

sets statoann autoreleased string.

when method exits, release called on statoann , no longer owns memory pointing to. when method called again when zoom or move map, memory statoann pointing used else (gmmgeotileimagedata in case). object not nsstring , doesn't have isequaltostring: method , error seeing.

to fix this, set statoann value retained doing in viewdidload. example, change to:

statoann = [[nsmutablestring alloc] initwithformat:@"true"]; 

you declare statoann property (@property (nonatomic, copy) nsstring *statoann) , set using self.statoann = @"true";. property setter retaining you.

however, don't need use string hold "true" , "false" value. it's easier , efficient use plain bool , won't have worry retain/release since it's primitive type , not object.

other thing viewforannotation not right place setting map view's region in first place. can in viewdidload after annotations added.

thing: @ top of viewforannotation, have comment "return nil current user location" code doesn't that. initializes view nil. comment says, need this:

mkpinannotationview *view = nil;   // return nil current user location... if ([annotation iskindofclass:[mkuserlocation class]])     return nil; 

finally, if dequeuereusableannotationviewwithidentifier return view (if view != nil), need set view.annotation current annotation since re-used view may have been different annotation.