如何在x个移动注解之间画线？

Question

Hai am new to xcode am developing an iOS app for vehicle tracking using mkmap I need to draw lines between the annotations for every 5 seconds based on the vehicle moving, My prob is it draw the line for the first time only and from the second refresh interval it it won't works my code is below,

- (void)viewDidLoad
{
   [super viewDidLoad];
   aTimer = [NSTimer scheduledTimerWithTimeInterval:5
                                                      target:self
                                                    selector:@selector(timerFired:)
                                                    userInfo:nil
                                                     repeats:YES];
}
-(void)timerFired:(NSTimer *) theTimer
{
    NSArray *existingpoints = MapViewC.annotations;
    if ([existingpoints count])
        [MapViewC removeAnnotations:existingpoints];
    NSString *urlMapString=[NSString stringWithFormat:@"http://www.logix.com/logix_webservice/map.php?format=json&truckno=%@",nam2];
    NSURL *urlMap=[NSURL URLWithString:urlMapString];
    NSData *dataMap=[NSData dataWithContentsOfURL:urlMap];
    NSError *errorMap;
    NSDictionary *jsonMap = [NSJSONSerialization JSONObjectWithData:dataMap options:kNilOptions error:&errorMap]; NSArray *resultsMap = [jsonMap valueForKey:@"posts"];
    NSArray *resMap = [resultsMap valueForKey:@"post"];
    NSArray *latitudeString=[resMap valueForKey:@"latitude"];
    NSString *latOrgstring = [latitudeString objectAtIndex:0];
    latitude=[latOrgstring doubleValue];
    NSArray *longitudeString=[resMap valueForKey:@"longitude"];
    NSString *longOrgstring = [longitudeString objectAtIndex:0];
    longitude=[longOrgstring doubleValue];
    NSString *ignation=[[resMap valueForKey:@"ignition"]objectAtIndex:0];
    //MAP VIEW Point
    MKCoordinateRegion myRegion;
    //Center
    CLLocationCoordinate2D center;
    center.latitude=latitude;
    center.longitude=longitude;
    //Span
    MKCoordinateSpan span;
    span.latitudeDelta=0.01f;
    span.longitudeDelta=0.01f;
    myRegion.center=center;
    myRegion.span=span;
    //Set our mapView
    [MapViewC setRegion:myRegion animated:YES];
    //Annotation
    //1.create coordinate for use with the annotation
    //CLLocationCoordinate2D wimbLocation;
    wimbLocation1.latitude=latitude;
    wimbLocation1.longitude=longitude;
    Annotation * myAnnotation= [Annotation alloc];
    CLLocation *someLocation=[[CLLocation alloc]initWithLatitude:latitude longitude:longitude];
    CLGeocoder *geocoder = [[CLGeocoder alloc] init];
    [geocoder reverseGeocodeLocation:someLocation completionHandler:^(NSArray *placemarks, NSError *error) {
        NSDictionary *dictionary = [[placemarks objectAtIndex:0] addressDictionary];
        addressOutlet=[dictionary valueForKey:@"Street"];
        City=[dictionary valueForKey:@"City"];
        State=[dictionary valueForKey:@"State"];
        myAnnotation.coordinate=wimbLocation1;
        if (addressOutlet!=NULL&&City!=NULL)
        {
            myAnnotation.title=addressOutlet;
            myAnnotation.subtitle=[NSString stringWithFormat:@"%@,%@", City, State];
        }
        [self.MapViewC addAnnotation:myAnnotation];
         [self line];
    }];
  }
  -(void)line
{
    CLLocationCoordinate2D coordinateArray[2];
    coordinateArray[0] = CLLocationCoordinate2DMake(latitude, longitude);
    coordinateArray[1] = CLLocationCoordinate2DMake(latitude, longitude);
    self.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:2];
    [self.MapViewC addOverlay:self.routeLine];


}
-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
    if(overlay == self.routeLine)
    {
        if(nil == self.routeLineView)
        {
            self.routeLineView = [[MKPolylineView alloc] initWithPolyline:self.routeLine];
            self.routeLineView.fillColor = [UIColor redColor];
            self.routeLineView.strokeColor = [UIColor redColor];
            self.routeLineView.lineWidth = 5;
        }
        return self.routeLineView;
    }
    return nil;
}

Kindly advice me to correct my errors. Thanks in advance...

Answer 1

Try this.... this will help you...

-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{

        {
            self.routeLineView = [[MKPolylineView alloc] initWithPolyline:self.routeLine];
            self.routeLineView.strokeColor = [UIColor redColor];
            self.routeLineView.lineWidth = 5;
        }
        return self.routeLineView;
}