我需要找出地图上的可见坐标。请检查我

Question

我需要找出地图上的可见坐标。请检查我。

CLLocationDegrees leftDegrees = mapView.region.center.longitude - (mapView.region.span.longitudeDelta / 2.0);
CLLocationDegrees rightdegrees = mapView.region.center.longitude + (mapView.region.span.longitudeDelta / 2.0);

CLLocationDegrees bottomDegrees = mapView.region.center.latitude - (mapView.region.span.latitudeDelta / 2.0);
CLLocationDegrees topDegrees = mapView.region.center.latitude + (mapView.region.span.latitudeDelta / 2.0);

if (leftDegrees > rightdegrees)
{
    [self getAnnotationFromServer: mapView.region.center andLeftDegrees:leftDegrees andRightDegrees:180 andBottomDegrees:bottomDegrees andTopDegrees:topDegrees];
    [self getAnnotationFromServer: mapView.region.center andLeftDegrees:rightdegrees andRightDegrees:-180 andBottomDegrees:bottomDegrees andTopDegrees:topDegrees];
}
else 
{
    [self getAnnotationFromServer: mapView.region.center andLeftDegrees:leftDegrees andRightDegrees:rightdegrees andBottomDegrees:bottomDegrees andTopDegrees:topDegrees];      
}

Answer 1

您的代码看起来不错，但是仅获取可见部分注释的简单方法是将中心和半径直接发送到服务器。您只需选择比屏幕对角线（latitudeDelta 或 longitudeDelta）稍大的半径，然后乘以常数即可。

这也对服务器有帮助，因为您可以轻松找到计算点之间距离的函数，而不必关心 180/-180 交汇点。