Adding MKPolyline Overlay to MKMapView crashes application

Question

My application was working fine on iOS6 but it is crashing on iOS 7 due to bad access when I add overlay to MKMapView.My code is as follows

MKPolyline *polyline = [[MKPolyline alloc] init];
   polyline = [MKPolyline polylineWithCoordinates:coordinates count:numberOfSteps];
    [directionMap addOverlay:polyline];

This is the crash log (lldb) bt *

 thread #51: tid = 0x1cc5, 0x38755f8c libdispatch.dylib`dispatch_retain$VARIANT$mp + 8, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
    frame #0: 0x38755f8c libdispatch.dylib`dispatch_retain$VARIANT$mp + 8
    frame #1: 0x3598dbc8 VectorKit`-[VKRasterOverlayTileSource init] + 176
    frame #2: 0x358cfd24 VectorKit`-[VKMapModel _rasterOverlayTileSourceForLevel:] + 308
    frame #3: 0x358d0226 VectorKit`-[VKMapModel addRasterOverlay:] + 46
    frame #4: 0x2f068dfe MapKit`-[MKOverlayContainerView _insertDrawable:forOverlay:atIndex:level:] + 1010
    frame #5: 0x2f06752e MapKit`-[MKOverlayContainerView _configureAndAddDrawable:forOverlay:level:] + 326
    frame #6: 0x2f0676ac MapKit`-[MKOverlayContainerView _considerAddingDrawable:inAddRect:level:] + 372
    frame #7: 0x2f067cce MapKit`-[MKOverlayContainerView addOverlay:level:] + 246
    frame #8: 0x001394c8 Falcon`-[GetDirectionVC showRouteFrom:to:](self=0x19742820, _cmd=0x001fa466, f=CLLocationCoordinate2D at 0x04f9ec2c, t=CLLocationCoordinate2D at 0x04f9ec1c) + 956 at GetDirectionVC.m:226
    frame #9: 0x001390ee Falcon`-[GetDirectionVC loadLocations](self=0x19742820, _cmd=0x001fa458) + 1314 at GetDirectionVC.m:173
    frame #10: 0x2e876e26 Foundation`__NSThread__main__ + 1062
    frame #11: 0x38891c1c libsystem_pthread.dylib`_pthread_body + 140
    frame #12: 0x38891b8e libsystem_pthread.dylib`_pthread_start + 102

(lldb)

Answer 1

I had the same problem, the stack trace looks misleading to me. My bugfix is to explicitely add the overlay on the main thread:

dispatch_async(dispatch_get_main_queue(), ^{
  [mapView addOverlay:myRouteLine];
});

or if you'd like to use the new MKOverlayRenderer:

dispatch_async(dispatch_get_main_queue(), ^{
  [mapView addOverlay:myRouteLine level:MKOverlayLevelAboveRoads];
});

In my case, I'm downloading asynchronously some data, generate Polylines, create MKOverlayViews / MKOverlayRenderes (didn't help to replace the deprecated code) and add the overlay to the map.