将MKMapView更新为从CLGeocoder返回的CLPlacemark [英] Updating MKMapView to CLPlacemark returned from CLGeocoder

问题描述

我希望能够通过允许用户在UIAlertView中输入地址或位置来更新MKMapView上显示的区域。我目前有：

I want to be able to update the region displayed on a MKMapView by allowing the user to type in an address or location in a UIAlertView. I currently have:

        if (geocoder.geocoding)
            [geocoder cancelGeocode];

        [geocoder geocodeAddressString:[[alertView textFieldAtIndex:0] text] completionHandler:^(NSArray *placemarks, NSError *error) {
            if (!error) {
                NSLog(@"Found a location");
            } else {
                NSLog(@"Error in geocoding");
            }

            NSLog(@"Num found: %d", [placemarks count]);

            CLPlacemark *placemark = [placemarks objectAtIndex:0];
            MKCoordinateRegion region;
            region.center.latitude = placemark.region.center.latitude;
            region.center.longitude = placemark.region.center.longitude;
            MKCoordinateSpan span;
            double radius = placemark.region.radius / 1000;

            NSLog(@"Radius is %f", radius);
            span.latitudeDelta = radius / 112.0;
            //span.longitudeDelta = ??? 

            region.span = span;

            NSLog(@"Region is %f %f %f", region.center.latitude, region.center.longitude, span.latitudeDelta);

            [mapView setRegion:region animated:YES];
        }];

我的问题是我不确定如何计算经度增量。

My problem is I am unsure how to calculate the longitude delta.

推荐答案

你可以设置它等于 latitudeDelta 和地图视图将根据需要进行调整。

You could just set it equal to latitudeDelta and the map view will adjust as needed.

但您首先不需要自己计算跨度。您可以使用：

But you don't need to calculate the span yourself in the first place. You can use:

region = MKCoordinateRegionMakeWithDistance(
             placemark.region.center, 
             placemark.region.radius, 
             placemark.region.radius);

不确定问题的第二部分。

---

在iOS 7及更高版本中，区域由 CLPlacemark 实际上是 CLCircularRegion （参见不推荐的CLRegion方法 - 如何获得半径？。

Not sure about the second part of your question.

---

In iOS 7 and higher, the region returned by the CLPlacemark is actually a CLCircularRegion (see Deprecated CLRegion methods - how to get radius?).

虽然原始代码仍然存在按原样工作，您可能会收到编译器警告， radius 和 center 已被弃用。

Although the original code will still work as-is, you may get a compiler warning that radius and center are deprecated.

为避免出现此警告，请将区域转换为 CLCircularRegion ：

To avoid the warning, cast the region as a CLCircularRegion:

CLCircularRegion *pmCircularRegion = (CLCircularRegion *)placemark.region;

region = MKCoordinateRegionMakeWithDistance(
         pmCircularRegion.center,
         pmCircularRegion.radius,
         pmCircularRegion.radius);

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