从MKMapView上的用户交互创建叠加层？
我有两个问题，
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如何从用户的触地事件创建MKMapkitView上的叠加层？ 即为了保持简单，用户触摸并创建MKCircle叠加层
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地图应用程序如何在触摸时实现“掉针”？ 有人知道或有一些关于如何完成类似事情的代码示例吗？
任何指针都将非常感激。 你可以看到，我一直在谷歌搜索并阅读大量的文档而没有太大的成功。
下面是一个示例，它创建一个圆圈并放下一个用户触摸并保持手指1秒的引脚。 它使用UILongPressGestureRecognizer，它在地图初始化的地方添加到mapView（例如viewDidLoad）。
确保也设置了mapView的委托。
// In viewDidLoad or where map is initialized... UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)]; lpgr.minimumPressDuration = 1.0; //user must hold for 1 second [mapView addGestureRecognizer:lpgr]; [lpgr release]; ... - (void)handleLongPress:(UIGestureRecognizer *)gestureRecognizer { if (gestureRecognizer.state != UIGestureRecognizerStateBegan) return; CGPoint touchPoint = [gestureRecognizer locationInView:mapView]; CLLocationCoordinate2D touchMapCoordinate = [mapView convertPoint:touchPoint toCoordinateFromView:mapView]; //add pin where user touched down... MKPointAnnotation *pa = [[MKPointAnnotation alloc] init]; pa.coordinate = touchMapCoordinate; pa.title = @"Hello"; [mapView addAnnotation:pa]; [pa release]; //add circle with 5km radius where user touched down... MKCircle *circle = [MKCircle circleWithCenterCoordinate:touchMapCoordinate radius:5000]; [mapView addOverlay:circle]; } -(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id)overlay { MKCircleView* circleView = [[[MKCircleView alloc] initWithOverlay:overlay] autorelease]; circleView.fillColor = [UIColor redColor]; return circleView; } - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id )annotation { static NSString *AnnotationIdentifier = @"Annotation"; MKPinAnnotationView* pinView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:AnnotationIdentifier]; if (!pinView) { pinView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:AnnotationIdentifier] autorelease]; pinView.pinColor = MKPinAnnotationColorGreen; pinView.animatesDrop = YES; } else { pinView.annotation = annotation; } return pinView; }