用mapkit进行地图的开发，经常要用到的就是计算两个地点间的距离问题，方法很简单：
CLLocationManager * locmanager = [[CLLocationManager alloc]init];//先定义一个cllocationmanager的实例
[locmanager setDelegate:self]; //设置代理为本身
[locmanager setDesiredAccuracy:kCLLocationAccuracyBest];//设置精确度为最准确
[locmanager startUpdatingLocation];//更新 location
//定义一个新的cllocation实例，下面会取得user location 和这个新的地点间的距离
CLLocation * newLocation = [[CLLocation alloc]initWithLatitude:32.0206410 longitude:118.7889040];
//为了方便查看，在这两个地点都添加标记，加到mapView中。
MapAnnotation * fuzimiaoAnnotation = [[MapAnnotation alloc]init];
fuzimiaoAnnotation.annotationType = myMapAnnotationTypeApple;
fuzimiaoAnnotation.title = @"Fu Zi Miao";
fuzimiaoAnnotation.coordinate = newLocation.coordinate;
MapAnnotation * newAnnotation = [[MapAnnotation alloc]init];
newAnnotation.title = @"You Current Location!";
newAnnotation.annotationType = myMapAnnotationTypeApple;
newAnnotation.coordinate = self.myCurrentLocation;
[self.locationMapView addAnnotation:newAnnotation];
[self.locationMapView selectAnnotation:newAnnotation animated:YES];
[self.locationMapView addAnnotation:fuzimiaoAnnotation];
[self.locationMapView selectAnnotation:fuzimiaoAnnotation animated:YES];
NSLog(@"%@",[NSString stringWithFormat:@"%0.2f km",[[locmanager location] distanceFromLocation:newLocation]/1000]);
//关键就在这里，取得两个cllocation间的距离，单位是m
CLLocationDistance newDistance = [[locmanager location] distanceFromLocation:newLocation];
//下面是设置mapView的显示区域，使得这两个地点都能出现在地图中，这里就用到了刚算出来的距离。
[self.locationMapView setRegion:MKCoordinateRegionMakeWithDistance(self.myCurrentLocation, newDistance, newDistance) animated:YES];
[newLocation release];
[fuzimiaoAnnotation release];
[newAnnotation release];