在iOS 7地图上显示路线：addOverlay无效

问题描述：

我希望在我的mapView中显示一个指向点的路线，我使用此代码创建路线：

i want display a point to point route inside my mapView, i use this code for create the route:

- (IBAction)backToYourCar {
    MKPlacemark *sourcePlacemark = [[MKPlacemark alloc] initWithCoordinate:self.annotationForCar.coordinate addressDictionary:nil];
    NSLog(@"coordiante : locationIniziale %f", sourcePlacemark.coordinate.latitude);
    MKMapItem *carPosition = [[MKMapItem alloc] initWithPlacemark:sourcePlacemark];
    MKMapItem *actualPosition = [MKMapItem mapItemForCurrentLocation];
    NSLog(@"coordiante : source %f, ActualPosition %f", carPosition.placemark.coordinate.latitude ,actualPosition.placemark.coordinate.latitude);
    MKDirectionsRequest *request = [[MKDirectionsRequest alloc] init];
    request.source = actualPosition;
    request.destination = carPosition;
    request.requestsAlternateRoutes = YES;

    MKDirections *directions = [[MKDirections alloc] initWithRequest:request];
    [directions calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
        if (error) {
            NSLog(@"Error : %@", error);
        }
        else {
            [self showDirections:response]; //response is provided by the CompletionHandler
        }
    }];
}

这用于在地图上显示路线：

and this for show the route on the map:

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

实际上这段代码什么都不做。

actually this code does nothing.

如果我尝试打印路线的距离我得到正确的值：

if i try to print the the distance of route i get the correct value:

route distance: 1910.000000

然后路线是对的，但我不明白为什么它没有出现在地图上！

then the route is right, but i can't understand why it doesn't appear on the map!

有任何建议吗？

答

我通过以下3个步骤解决了研究日：

after a day of research i have solved with this 3 steps:

设置委托（ self.mapView.delegate = self ）。

导入 MKMapViewDelegate

实施新的iOS7 MapView委托方法：
- （MKOverlayRenderer *）mapView：（MKMapView *）mapView rendererForOverlay（id< MKOverlay>）overlay ：

Set the delegate (self.mapView.delegate = self).
import the MKMapViewDelegate
Implemente the new iOS7 MapView delegate method: - (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay(id<MKOverlay>)overlay:

这是我的实施：

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
    if ([overlay isKindOfClass:[MKPolyline class]]) {
        MKPolyline *route = overlay;
        MKPolylineRenderer *routeRenderer = [[MKPolylineRenderer alloc] initWithPolyline:route];
        routeRenderer.strokeColor = [UIColor blueColor];
        return routeRenderer;
    }
    else return nil;
}

在地图上添加折线时，委托会自动调用此方法。

this method is automatically called by the delegate when you add the polyline on the map.

在iOS 7地图上显示路线：addOverlay无效

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