mapView中添加polyline

想在MapView中添加Polyline。代码如下：

CLLocationCoordinate2D coord[2];
coord[1].latitude = 45.42207;
coord[1].longitude = 9.123888;
coord[2].latitude = 45.422785;
coord[2].longitude = 9.12377;

MKPolyline *polyline = [[MKPolyline alloc] init];
polyline = [MKPolyline polylineWithCoordinates:coord count:2];

[self.mapView addAnnotation:polyline];

但是报错： EXC_BAD_ACCESS.

试试：

CLLocationCoordinate2D coord[2];
coord[0].latitude = 45.42207;
coord[0].longitude = 9.123888;
coord[1].latitude = 45.422785;
coord[1].longitude = 9.12377;

MKPolyline *polyline = [[MKPolyline alloc] init];
polyline = [MKPolyline polylineWithCoordinates:coord count:2];


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

    MKPolylineView *polyLineView = [[MKPolylineView alloc] initWithPolyline:polyline];
    polyLineView.fillColor = [UIColor blueColor];
    polyLineView.strokeColor = [UIColor greenColor];
    polyLineView.lineWidth = 7;
    return polyLineView;
}