简易绘制地图路线

当我们获取了一组地理位置后，可能会想要在地图上绘制这组地理位置信息所包含的路线。

MKMapView提供了addOverlay功能（以及addAnnotation），让我们可以在地图上放一层遮罩。如果要放一组遮罩，可以用addOverlays。

 #pragma mark -

 - (void)drawLineWithLocationArray:(NSArray *)locationArray
 {
     int pointCount = [locationArray count];
     CLLocationCoordinate2D *coordinateArray = (CLLocationCoordinate2D *)malloc(pointCount * sizeof(CLLocationCoordinate2D));

     for (int i = 0; i < pointCount; ++i) {
         CLLocation *location = [locationArray objectAtIndex:i];
         coordinateArray[i] = [location coordinate];
     }

     self.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:pointCount];
     [self.mapView setVisibleMapRect:[self.routeLine boundingMapRect]];
     [self.mapView addOverlay:self.routeLine];

     free(coordinateArray);
     coordinateArray = NULL;
 }

MKPolyLine 为我们提供了方便绘制多条线段的功能，它实现了MKOverlay协议，但并不能作为遮罩。我们需要实现相应的遮罩代理方法：

 #pragma mark - MKMapViewDelegate

 - (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id)overlay
 {
     if(overlay == self.routeLine) {
         if(nil == self.routeLineView) {
             self.routeLineView = [[[MKPolylineView alloc] initWithPolyline:self.routeLine] autorelease];
             self.routeLineView.fillColor = [UIColor redColor];
             self.routeLineView.strokeColor = [UIColor redColor];
             self.routeLineView.lineWidth = 5;
         }
         return self.routeLineView;
     }
     return nil;
 }

下面是我的测试代码，用北京的经纬度和杭州的经纬度画线：

 - (void)drawTestLine
 {
     CLLocation *location0 = [[CLLocation alloc] initWithLatitude:39.954245 longitude:116.312455];
     CLLocation *location1 = [[CLLocation alloc] initWithLatitude:30.247871 longitude:120.127683];
     NSArray *array = [NSArray arrayWithObjects:location0, location1, nil];
     [self drawLineWithLocationArray:array];
 }