MKMapView - 缩放以适应用户位置周围最近的注释答案

【问题标题】：MKMapView - Zoom to fit nearest annotations around userlocationMKMapView - 缩放以适应用户位置周围最近的注释
【发布时间】：2014-02-06 15:19:44
【问题描述】：

我想缩放我的地图视图以显示最近注释中的至少一个注释，以尽可能高的缩放比例和用户位置。我尝试了以下方法：

-(void)zoomToFitNearestAnnotationsAroundUserLocation {


    MKMapPoint userLocationPoint = MKMapPointForCoordinate(self.restaurantsMap.userLocation.coordinate);
    MKCoordinateRegion region;
    if ([self.restaurantsMap.annotations count] > 1) {

        for (id<MKAnnotation> annotation in self.restaurantsMap.annotations) {

          MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
          CLLocationDistance distanceBetweenAnnotationsAndUserLocation = MKMetersBetweenMapPoints(annotationPoint, userLocationPoint);


             region =  MKCoordinateRegionMakeWithDistance(self.restaurantsMap.userLocation.coordinate, distanceBetweenAnnotationsAndUserLocation, distanceBetweenAnnotationsAndUserLocation);


        }

        [self.restaurantsMap setRegion:region animated:YES];

    }



}

我将如何设法保存 2-3 个最近距离并根据该信息创建一个区域？

【问题讨论】：

标签： ios iphone mkmapview

【解决方案1】：

如果您正在为 iOS 7 及更高版本进行开发，您可以保存一组按用户位置与注释之间的距离排序的注释，然后获取前 3 个注释。一旦你有了这些，你可以使用showAnnotations:animated: 来定位地图，以便所有注释都可见。

这是另一种方式（取自here）：

MKMapRect zoomRect = MKMapRectNull;
for (id <MKAnnotation> annotation in mapView.annotations)
{
    MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
    MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0.1, 0.1);
    zoomRect = MKMapRectUnion(zoomRect, pointRect);
}
[mapView setVisibleMapRect:zoomRect animated:YES];

//You could also update this to include the userLocation pin by replacing the first line with
MKMapPoint annotationPoint = MKMapPointForCoordinate(mapView.userLocation.coordinate);
MKMapRect zoomRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0.1, 0.1);

当然，您必须更新第二个解决方案以仅使用最近的注释点，但您已经知道如何找到它们，所以这不成问题。

【讨论】：

【解决方案2】：

将注释存储在数组中

添加此功能并根据需要更改距离

- (MKCoordinateRegion)regionForAnnotations:(NSArray *)annotations
{
MKCoordinateRegion region;

if ([annotations count] == 0)
{
    region = MKCoordinateRegionMakeWithDistance(_mapView.userLocation.coordinate, 1000, 1000);
}

else if ([annotations count] == 1)
{
    id <MKAnnotation> annotation = [annotations lastObject];
    region = MKCoordinateRegionMakeWithDistance(annotation.coordinate, 1000, 1000);
} else {
    CLLocationCoordinate2D topLeftCoord;
    topLeftCoord.latitude = -90;
    topLeftCoord.longitude = 180;

    CLLocationCoordinate2D bottomRightCoord;
    bottomRightCoord.latitude = 90;
    bottomRightCoord.longitude = -180;

    for (id <MKAnnotation> annotation in annotations)
    {
        topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);
        topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
        bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
        bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
    }

    const double extraSpace = 1.12;
    region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) / 2.0;
    region.center.longitude = topLeftCoord.longitude - (topLeftCoord.longitude - bottomRightCoord.longitude) / 2.0;
    region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * extraSpace;
    region.span.longitudeDelta = fabs(topLeftCoord.longitude - bottomRightCoord.longitude) * extraSpace;
}

return [self.mapView regionThatFits:region];
}

然后这样称呼它

 MKCoordinateRegion region = [self regionForAnnotations:_locations];
[self.mapView setRegion:region animated:YES];

现在缩放应该适合数组中的所有注释

祝你好运！！

【讨论】：