在ios中，如何实现MapView（Route）？

Question

我想在MapView中显示点对点路线，我使用此代码创建路线：

- (void)getDirections
{
     //MKMapItem *srcMapItem = [MKMapItem mapItemForCurrentLocation];

MKPlacemark *source = [[MKPlacemark alloc]initWithCoordinate:CLLocationCoordinate2DMake(13.0833, 80.2333) addressDictionary:[NSDictionary dictionaryWithObjectsAndKeys:@"",@"", nil] ];
MKMapItem *srcMapItem = [[MKMapItem alloc]initWithPlacemark:source];

MKPlacemark *destination = [[MKPlacemark alloc]initWithCoordinate:CLLocationCoordinate2DMake(13.0983, 80.1622) addressDictionary:[NSDictionary dictionaryWithObjectsAndKeys:@"",@"", nil] ];
MKMapItem *desMapItem = [[MKMapItem alloc]initWithPlacemark:destination];

MKDirectionsRequest *request = [[MKDirectionsRequest alloc] init];
//request.source = [MKMapItem mapItemForCurrentLocation];
request.source = srcMapItem;
request.destination = desMapItem;
request.requestsAlternateRoutes = NO;

MKDirections *directions = [[MKDirections alloc] initWithRequest:request];

[directions calculateDirectionsWithCompletionHandler: ^(MKDirectionsResponse *response, NSError *error) {
    if (error) {
        // Handle error
    } else {
        [self showRoute:response];
    }
}];
}


-(void)showRoute:(MKDirectionsResponse *)response
{
for (MKRoute *route in response.routes)
{
    [self.Route_Map addOverlay:route.polyline level:MKOverlayLevelAboveRoads];

    for (MKRouteStep *step in route.steps)
    {
        NSLog(@"%@", step.instructions);
    }
}
}

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id < MKOverlay >)overlay
{
MKPolylineRenderer *renderer = [[MKPolylineRenderer alloc] initWithOverlay:overlay];
renderer.strokeColor = [UIColor redColor];
renderer.lineWidth = 10.0;
return renderer;
}

地图视图路线代码无效。有人发现错误吗？

有什么建议吗？

替换代码：

MKPlacemark *source = [[MKPlacemark alloc] initWithCoordinate: CLLocationCoordinate2DMake(37.776142, -122.424774) addressDictionary:[NSDictionary dictionaryWithObjectsAndKeys:@"",@"", nil]];

MKPlacemark *destination = [[MKPlacemark alloc] initWithCoordinate: CLLocationCoordinate2DMake(37.73787, -122.373962) addressDictionary:[NSDictionary dictionaryWithObjectsAndKeys:@"",@"", nil]];

现在正在工作。除了此代码之外，为什么路由映射不起作用？

有什么建议吗？