如何比较两个不同的地图视图区域并找出它们之间的差异

Question

[伙计们，我正在开发Map-view Base应用程序。我几乎已经完成了地图视图的所有操作，但是无法比较两个不同的地图视图区域并找到新的地图视图区域。例如，如果用户拖动地图，我想查找该区域已更改了多少。

Answer 1

此答案显示了如何比较两个地图点。您可以在地图区域的中心使用它：link。

Answer 2

部分答案。平等遵守MKCoordinateRegion

 extension MKCoordinateRegion: Equatable
 {
    public static func == (lhs: MKCoordinateRegion, rhs: MKCoordinateRegion) -> Bool
    {
        if lhs.center.latitude != rhs.center.latitude || lhs.center.longitude != rhs.center.longitude
        {
            return false
        }
        if lhs.span.latitudeDelta != rhs.span.latitudeDelta || lhs.span.longitudeDelta != rhs.span.longitudeDelta
        {
            return false
        }
        return true
    }
 }

Answer 3

首先，您需要找到初始地图区域。假设您的地图名为mapView ...，您可以首先在（viewDidLoad）中找到它：

CLLocationCoordinate2D center = mapView.centerCoordinate;
CLLocationDegrees lat = center.latitude;
CLLocationDegrees lon = center.longitude;

MKCoordinateRegion region = mapView.region;
MKCoordinateSpan span = region.span;

//Assuming they have been declared as instance variables of type double
current_lat_low = lat - span.latitudeDelta / 2.0;
current_lat_high = lat + span.latitudeDelta / 2.0;
current_lon_low = lon - span.longitudeDelta / 2.0;
current_lon_high = lon + span.longitudeDelta / 2.0;

这将为您显示地图的初始区域。然后在

- (void)mapView:(MKMapView*)mapView regionDidChangeAnimated:(BOOL)animated
{

    CLLocationCoordinate2D center = mapView.centerCoordinate;
    CLLocationDegrees lat = center.latitude;
    CLLocationDegrees lon = center.longitude;

    MKCoordinateRegion region = mapView.region;
    MKCoordinateSpan span = region.span;

    double lat_low = lat - span.latitudeDelta / 2.0;
    double lat_high = lat + span.latitudeDelta / 2.0;
    double lon_low = lon - span.longitudeDelta / 2.0;
    double lon_high = lon + span.longitudeDelta / 2.0;

    //do any work comparing the initial lat/lons with the new values
    .....

    //set current lat/lon to be the new lat/lon after work is complete
    current_lat_low = lat_low;
    current_lat_high = lat_high;
    current_lon_low = lon_low;
    current_lon_high = lon_high;
}