iOS：放大和缩小地图效果

Question

我已经创建了此链接上显示的地图，并且它运行良好。

但问题是，它只能以一种方式放大（只会变大）。 我怎样才能让它以任何一种方式工作？

可能就像我们在谷歌地图上看到的一样（左边的加号 - 减号）。

Answer 1

用于放大

-(void)zoomIn
{
    region.span.latitudeDelta = region.span.latitudeDelta/4 ;
    region.span.longitudeDelta = region.span.longitudeDelta/4;



    region.center.latitude = mapView.centerCoordinate.latitude ;
    region.center.longitude = mapView.centerCoordinate.longitude ;
    [mapView setRegion:region animated:YES];
}

对于缩小

-(void)zoomOut
{
    region.span.latitudeDelta = region.span.latitudeDelta*4 ;
    region.span.longitudeDelta = region.span.longitudeDelta*4;



    region.center.latitude = mapView.centerCoordinate.latitude ;
    region.center.longitude = mapView.centerCoordinate.longitude ;
    [mapView setRegion:region animated:YES];
}

您可以使用此结构中的 delta 值来指示所需的地图缩放级别，较小的 delta 值对应于较高的缩放级别。

请参阅此链接了解更多信息。

Answer 2

这是 Midhun VP 和 Slavco Petkovski 的答案的修订版，它在将 latitudeDelta 设置得太大时避免了 zoomOut 中“无效区域”的 NSInvalidArgumentException。 放大似乎没有任何问题——它只是在达到极限后不再放大。

- (void)zoomIn {
    MKCoordinateRegion region = [self.mapView region];
    region.span.latitudeDelta = region.span.latitudeDelta/4;
    region.span.longitudeDelta = region.span.longitudeDelta/4;
    region.center.latitude = self.mapView.centerCoordinate.latitude;
    region.center.longitude = self.mapView.centerCoordinate.longitude;
    [self.mapView setRegion:region animated:YES];
    //NSLog(@"zoomIn: center %lf, %lf; spanDelta %lf, %lf, upper left %lf, %lf; lower right %lf %lf", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta, region.center.latitude + region.span.latitudeDelta / 2, region.center.longitude - region.span.longitudeDelta / 2, region.center.latitude - region.span.latitudeDelta / 2, region.center.longitude + region.span.longitudeDelta / 2);
}

- (void)zoomOut {
    MKCoordinateRegion region = [self.mapView region];
    region.span.latitudeDelta = region.span.latitudeDelta*4;
    region.span.longitudeDelta = region.span.longitudeDelta*4;
    region.center.latitude = self.mapView.centerCoordinate.latitude;
    region.center.longitude = self.mapView.centerCoordinate.longitude;

    // The region upper latitude must not exceed 90.0 degrees, and the region lower latitude must not fall below -90.0.
    double upperLatitude = region.center.latitude + region.span.latitudeDelta / 2.0;
    double lowerLatitude = region.center.latitude - region.span.latitudeDelta / 2.0;
    if ( upperLatitude > 90 || lowerLatitude < -90 ) {
        region.center.latitude = 0.0;
        double spanRatio = region.span.latitudeDelta / region.span.longitudeDelta;
        region.span.latitudeDelta = 180;
        region.span.longitudeDelta = 180 / spanRatio;
    }
    [self.mapView setRegion:region animated:YES];
    //NSLog(@"zoomOut: center %lf, %lf; spanDelta %lf, %lf, upper left %lf, %lf; lower right %lf %lf", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta, region.center.latitude + region.span.latitudeDelta / 2, region.center.longitude - region.span.longitudeDelta / 2, region.center.latitude - region.span.latitudeDelta / 2, region.center.longitude + region.span.longitudeDelta / 2);
}