如何将 MKCircleView 的一个位置移动到 MKMapView 中的另一个位置？答案

【问题标题】：How to Move MKCircleView at one position to another position in MKMapView?如何将 MKCircleView 的一个位置移动到 MKMapView 中的另一个位置？
【发布时间】：2013-08-23 13:55:53
【问题描述】：

我正在使用 MkCircle 声明位置现在我必须在 MKMapView（拖放）中将圆形位置更改为另一个位置。我怎么能做到这一点。任何帮助将不胜感激。

【问题讨论】：

标签： ios objective-c touch mkmapview uitapgesturerecognizer

【解决方案1】：

首先，我建议您使用一些类属性来跟踪覆盖：

@property (nonatomic, weak) MKCircle *overlay;

然后，定义一个UIPanGestureRecognizer 来执行拖放操作：

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
[self.mapView addGestureRecognizer:pan];

要使手势可取消，您应该导入以下标头：

#import <UIKit/UIGestureRecognizerSubclass.h>

您需要为此手势识别器编写一个处理程序，为您拖动的位置添加一个覆盖并删除旧的（但如果手势没有从覆盖上开始，则取消该手势）：

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static CGPoint originalPoint;

    if (gesture.state == UIGestureRecognizerStateBegan) {
        CGPoint point = [gesture locationInView:gesture.view];
        CLLocationCoordinate2D tapCoordinate = [self.mapView convertPoint:point toCoordinateFromView:gesture.view];
        CLLocation *tapLocation = [[CLLocation alloc] initWithLatitude:tapCoordinate.latitude longitude:tapCoordinate.longitude];

        CLLocationCoordinate2D originalCoordinate = [self.overlay coordinate];
        CLLocation *originalLocation = [[CLLocation alloc] initWithLatitude:originalCoordinate.latitude longitude:originalCoordinate.longitude];

        if ([tapLocation distanceFromLocation:originalLocation] > [self.overlay radius]) {
            gesture.state = UIGestureRecognizerStateCancelled;
            return;
        }
        else
            originalPoint = [self.mapView convertCoordinate:originalCoordinate toPointToView:gesture.view];
    }

    if (gesture.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [gesture translationInView:gesture.view];
        CGPoint newPoint    = CGPointMake(originalPoint.x + translation.x, originalPoint.y + translation.y);

        CLLocationCoordinate2D newCoordinate = [self.mapView convertPoint:newPoint toCoordinateFromView:gesture.view];

        MKCircle *circle = [MKCircle circleWithCenterCoordinate:newCoordinate radius:[self.overlay radius]];
        [self.mapView addOverlay:circle];
        [self.mapView removeOverlay:self.overlay];
        self.overlay = circle;
    }
}

注意，地图的scrollEnabled 必须关闭才能识别此手势。

【讨论】：