使用IBAction按钮缩放MapView

Question

我有个问题。我的当前位置在地图视图中显示并居中，但是地图区域不会放大。我尝试采纳了Rob的建议，从didUpdateToLocation方法中去掉了span和region，但我肯定没有正确地实现它。我认为它不能识别我在viewDidLoad中对setRegion的调用，也不能识别我的按钮。请检查我下面的代码并指出错误。我的目标是能够使用IBAction按钮放大和缩小我所在的位置。

.h

- (IBAction)zoomIn:(id)sender;

- (IBAction)zoomOut:(id)sender;

viewDidLoad中的.m

double miles = 0.5;

MKCoordinateSpan span;
span.latitudeDelta = miles/69.0;
span.longitudeDelta = miles/69.0;

MKCoordinateRegion region;
region.span = span;

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

[self.mapView setUserTrackingMode:MKUserTrackingModeFollow animated:YES];

_mapView.mapType = MKMapTypeSatellite;

我的didUpdateToLocation方法中的.m。

[self.mapView setCenterCoordinate:newLocation.coordinate animated:YES];

.Zoom In：

- (IBAction)zoomIn:(id)sender 
{
    MKCoordinateSpan span;
    span.latitudeDelta = _mapView.region.span.latitudeDelta * 2;
    span.longitudeDelta = _mapView.region.span.latitudeDelta * 2;
    MKCoordinateRegion region;
    region.span = span;
    region.center = _mapView.region.center;

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

.Zoom输出：

- (IBAction)zoomOut:(id)sender
{
     MKCoordinateSpan span;
     span.latitudeDelta = _mapView.region.span.latitudeDelta / 2;
     span.longitudeDelta = _mapView.region.span.latitudeDelta / 2;
     MKCoordinateRegion region;
     region.span = span;
     region.center = _mapView.region.center;

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

Answer 1

您可以获取当前的region，根据需要将span乘以或除以2(放大时除以，缩小时乘以)，然后设置region

- (IBAction)zoomIn:(id)sender {
    MKCoordinateRegion region = self.mapView.region;
    region.span.latitudeDelta /= 2.0;
    region.span.longitudeDelta /= 2.0;
    [self.mapView setRegion:region animated:YES];
}

- (IBAction)zoomOut:(id)sender {
    MKCoordinateRegion region = self.mapView.region;
    region.span.latitudeDelta  = MIN(region.span.latitudeDelta  * 2.0, 180.0);
    region.span.longitudeDelta = MIN(region.span.longitudeDelta * 2.0, 180.0);
    [self.mapView setRegion:region animated:YES];
}

如果您希望地图自动缩放到您的位置，您可以使用：

self.mapView.userTrackingMode = MKUserTrackingModeFollow;

如果您想手动完成此操作，可以执行以下操作。首先，为您是否已经放大定义一个类属性：

@property (nonatomic) BOOL alreadySetZoomScale;

然后更改didUpdateLocations (或didUpdateToLocation)以选中此选项，并设置缩放比例一次：

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    CLLocation* newLocation = [locations lastObject]; // if less than zero, then valid lat and long not found

    if (newLocation.horizontalAccuracy < 0)
        return;

    if (!self.alreadySetZoomScale)
    {
        MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(newLocation.coordinate, 1609, 1609); // 1 mile = 1609.34 meters
        self.mapView.region = region;
        [self.mapView setRegion:region animated:YES];
        self.alreadySetZoomScale = YES;
    }
    else
    {
        [self.mapView setCenterCoordinate:newLocation.coordinate animated:YES];
    }
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    // if prior to iOS 6, use this old `MKMapViewDelegate` method, but call our
    // other routine.

    if (SYSTEM_VERSION_LESS_THAN(@"6.0"))
        [self locationManager:manager didUpdateLocations:@[newLocation]];
}

这基本上是说，“如果我还没有放大，根据newLocation和该位置周围一定的米数来设置区域，但如果我已经这样做了，就根据我当前的位置设置中心坐标，但不要改变缩放比例(如果我已经放大或缩小了)。这也做了一些有条件的iOS版本号逻辑(使用macros shown here)，以确保最终用户运行的是iOS 6.0之前的版本，它将调用我们的更新方法。

顺便说一下，如果你在地图上显示用户位置(例如self.mapView.showsUserLocation = YES;)，你可能想让这个didUpdateLocations在移动地图中心之前也移除与MKUserLocation相关的覆盖，否则它可能会留下旧的覆盖：

[self.mapView removeOverlays:self.mapView.overlays];

Answer 2

尝尝这个。但我还没有测试过。

- (IBAction)zoomIn:(id)sender {
      MKCoordinateSpan span;
      span.latitudeDelta = _mapView.region.span.latitudeDelta * 2;
      span.longitudeDelta = _mapView.region.span.latitudeDelta * 2;
      MKCoordinateRegion region;
      region.span = span;
      region.center = _mapView.region.center;

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

 - (IBAction)zoomOut:(id)sender {
      MKCoordinateSpan span;
      span.latitudeDelta = _mapView.region.span.latitudeDelta / 2;
      span.longitudeDelta = _mapView.region.span.latitudeDelta / 2;
      MKCoordinateRegion region;
      region.span = span;
      region.center = _mapView.region.center;

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

 }

Answer 3

好了，这是我最后用来让我的两个IBAction按钮(zoomIn和zoomOut)与我的mapView一起工作的东西。打开应用程序时，将显示用户位置，地图将放大并围绕其居中。然后你可以使用按钮放大或缩小2倍。*非常感谢Rob给我指路。

.h

- (IBAction)zoomIn:(id)sender;

- (IBAction)zoomOut:(id)sender;

.m

@interface LocationViewController ()

@property (nonatomic) BOOL alreadySetZoomScale;

@end



-(void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
      fromLocation:(CLLocation *)oldLocation {


if (!_alreadySetZoomScale)
{
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(newLocation.coordinate,    1609, 1609); // 1 mile = 1609.34 meters

self.mapView.region = region;
[self.mapView setRegion:region animated:YES];
_alreadySetZoomScale = YES;

}

else

{
[self.mapView setCenterCoordinate:newLocation.coordinate animated:YES];
}


- (IBAction)zoomIn:(id)sender {

MKCoordinateRegion region = self.mapView.region;
region.span.latitudeDelta /= 2.0;
region.span.longitudeDelta /= 2.0;
self.mapView.region = region;

}

- (IBAction)zoomOut:(id)sender {;

MKCoordinateRegion region = self.mapView.region;
region.span.latitudeDelta *= 2.0;
region.span.longitudeDelta *= 2.0;
self.mapView.region = region;

}

在viewDidLoad中，我还有其他几个对MKMapView的调用，比如self.mapView.showsUserLocation = YES；，但差不多就这些了。