iOS mapkit MKPolyline查看不显示长途

Question

对iOS [用户跟踪视图]使用Map kit MKPolylineView。它显示了一些特定的距离，但没有显示长距离。

这是我的代码：

-(void)viewDidLoad { [super viewDidLoad];

    appdelegate=[[UIApplication sharedApplication]delegate];

   // Do any additional setup after loading the view, typically from a
    nib.

     self.mapView=[[MKMapView
    alloc]initWithFrame:CGRectMake(0, 0, 320, 568)];
    self.mapView.delegate = self; self.mapView.showsUserLocation = YES;
    self.mapView.userInteractionEnabled = YES;        //
    self.mapView.userTrackingMode = MKUserTrackingModeFollowWithHeading;

    [self.view addSubview:self.mapView];        
    [self configureRoutes];

}

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
    NSLog(@"%@ test 2----- %@", self, NSStringFromSelector(_cmd));

    MKOverlayView* overlayView = nil;

    if(overlay == self.routeLine)
    {
        //if we have not yet created an overlay view for this overlay, create it now.

       // if (self.routeLineView) {
          // [self.routeLineView removeFromSuperview];
       // }

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

        overlayView = self.routeLineView;       
    }

    return overlayView;
}