iOS MKMapView 缩放以显示所有标记

Question

我正在使用 MKMapView 并在地图上绘制了几个点。我已经使用 MKCooperativeRegion 和 MKCooperativeSpan 来启用围绕其中一个点的缩放等 - 但这不是我想要的......

我正在尝试使用类似于Javascript 缩放至边界功能。所以我的所有观点都应该对用户可见。 （英国各地大约有 10 个点）我想将它们全部展示出来，或者如果其中大部分位于伦敦地区，请放大到那里。

有没有办法以编程方式解决这个问题？

Answer 1

当然。您想要找到注释中最大和最小的纬度和经度值（可以通过迭代 map.annotations 来实现），然后设置地图以显示所有这些值。

// pad our map by 10% around the farthest annotations
#define MAP_PADDING 1.1

// we'll make sure that our minimum vertical span is about a kilometer
// there are ~111km to a degree of latitude. regionThatFits will take care of
// longitude, which is more complicated, anyway. 
#define MINIMUM_VISIBLE_LATITUDE 0.01

MKCoordinateRegion region;
region.center.latitude = (minLatitude + maxLatitude) / 2;
region.center.longitude = (minLongitude + maxLongitude) / 2;

region.span.latitudeDelta = (maxLatitude - minLatitude) * MAP_PADDING;

region.span.latitudeDelta = (region.span.latitudeDelta < MINIMUM_VISIBLE_LATITUDE)
    ? MINIMUM_VISIBLE_LATITUDE 
    : region.span.latitudeDelta;

region.span.longitudeDelta = (maxLongitude - minLongitude) * MAP_PADDING;

MKCoordinateRegion scaledRegion = [map regionThatFits:region];
[map setRegion:scaledRegion animated:YES];

Answer 2

如果您仅针对 iOS 7 或更高版本，您现在可以使用：

- (void)showAnnotations:(NSArray *)annotations 
               animated:(BOOL)animated

Answer 3

这是一项改进，考虑了您叠加到地图上的注释视图的高度（例如，当注释的坐标偏移位于底部时，注释的顶部不会被切断）。或者进一步概括，允许您以像素为单位而不是百分比指定填充。它需要一个两阶段的过程，您可以找出注释的边界，然后进一步增加边界以考虑您的地图填充。

- (void) zoomToAnnotationsBounds:(NSArray *)annotations {

CLLocationDegrees minLatitude = DBL_MAX;
CLLocationDegrees maxLatitude = -DBL_MAX;
CLLocationDegrees minLongitude = DBL_MAX;
CLLocationDegrees maxLongitude = -DBL_MAX;

for (MyAnnotation *annotation in annotations) {
            double annotationLat = annotation.coordinate.latitude;
            double annotationLong = annotation.coordinate.longitude;
    minLatitude = fmin(annotationLat, minLatitude);
    maxLatitude = fmax(annotationLat, maxLatitude);
    minLongitude = fmin(annotationLong, minLongitude);
    maxLongitude = fmax(annotationLong, maxLongitude);
}

    // See function below
[self setMapRegionForMinLat:minLatitude minLong:minLongitude maxLat:maxLatitude maxLong:maxLongitude];

// If your markers were 40 in height and 20 in width, this would zoom the map to fit them perfectly. Note that there is a bug in mkmapview's set region which means it will snap the map to the nearest whole zoom level, so you will rarely get a perfect fit. But this will ensure a minimum padding.
UIEdgeInsets mapPadding = UIEdgeInsetsMake(40.0, 10.0, 0.0, 10.0);
CLLocationCoordinate2D relativeFromCoord = [self.mapView convertPoint:CGPointMake(0, 0) toCoordinateFromView:self.mapView];

// Calculate the additional lat/long required at the current zoom level to add the padding
CLLocationCoordinate2D topCoord = [self.mapView convertPoint:CGPointMake(0, mapPadding.top) toCoordinateFromView:self.mapView];
CLLocationCoordinate2D rightCoord = [self.mapView convertPoint:CGPointMake(0, mapPadding.right) toCoordinateFromView:self.mapView];
CLLocationCoordinate2D bottomCoord = [self.mapView convertPoint:CGPointMake(0, mapPadding.bottom) toCoordinateFromView:self.mapView];
CLLocationCoordinate2D leftCoord = [self.mapView convertPoint:CGPointMake(0, mapPadding.left) toCoordinateFromView:self.mapView];

double latitudeSpanToBeAddedToTop = relativeFromCoord.latitude - topCoord.latitude;
double longitudeSpanToBeAddedToRight = relativeFromCoord.latitude - rightCoord.latitude;
double latitudeSpanToBeAddedToBottom = relativeFromCoord.latitude - bottomCoord.latitude;
double longitudeSpanToBeAddedToLeft = relativeFromCoord.latitude - leftCoord.latitude;

maxLatitude = maxLatitude + latitudeSpanToBeAddedToTop;
minLatitude = minLatitude - latitudeSpanToBeAddedToBottom;

maxLongitude = maxLongitude + longitudeSpanToBeAddedToRight;
minLongitude = minLongitude - longitudeSpanToBeAddedToLeft;

[self setMapRegionForMinLat:minLatitude minLong:minLongitude maxLat:maxLatitude maxLong:maxLongitude];
}

-(void) setMapRegionForMinLat:(double)minLatitude minLong:(double)minLongitude maxLat:(double)maxLatitude maxLong:(double)maxLongitude {

    MKCoordinateRegion region;
    region.center.latitude = (minLatitude + maxLatitude) / 2;
    region.center.longitude = (minLongitude + maxLongitude) / 2;
    region.span.latitudeDelta = (maxLatitude - minLatitude);
    region.span.longitudeDelta = (maxLongitude - minLongitude);

    // MKMapView BUG: this snaps to the nearest whole zoom level, which is wrong- it doesn't respect the exact region you asked for. See http://stackoverflow.com/questions/1383296/why-mkmapview-region-is-different-than-requested
    [self.mapView setRegion:region animated:YES];
}

Answer 4

这是一个老问题，我知道您可能不需要任何帮助。但我只是将其提供给那些现在正在寻找方法的人，因为从 iOS 7 开始，MKMapView 中有一个新方法可以使用。它既干净又简单。

声明

环球银行金融电信协会

func showAnnotations(_ 注释: [AnyObject]!,
            动画动画：Bool)

目标-C

- (void)showAnnotations:(NSArray *)annotations
               动画：(BOOL)动画

参数

annotations 您希望在其中可见的注释
地图。动画是，如果您希望地图区域更改为
动画，如果您希望地图显示新区域，则为“否”
立即没有动画。

讨论

调用此方法更新
区域属性中的值以及可能的其他属性
反映新的地图区域。

Answer 5

修改后的答案与所有​​完美的工作代码。

//Zooming the ploted Area
- (void)zoomToAnnotationsBounds:(NSArray *)latLongArray {
        __block CLLocationDegrees minLatitude = DBL_MAX;
        __block CLLocationDegrees maxLatitude = -DBL_MAX;
        __block CLLocationDegrees minLongitude = DBL_MAX;
        __block CLLocationDegrees maxLongitude = -DBL_MAX;

        [latLongArray enumerateObjectsUsingBlock:^(NSString *latLongObj, NSUInteger latLongIdx, BOOL *stop) {
            latLongObj = [latLongArray objectAtIndex:latLongIdx];
            NSArray *latLongPoint = [latLongObj componentsSeparatedByString:@","];

            double annotationLat = [[latLongPoint objectAtIndex:0] doubleValue];
            double annotationLong = [[latLongPoint objectAtIndex:1] doubleValue];
            minLatitude = fmin(annotationLat, minLatitude);
            maxLatitude = fmax(annotationLat, maxLatitude);
            minLongitude = fmin(annotationLong, minLongitude);
            maxLongitude = fmax(annotationLong, maxLongitude);
        }];

        [self setMapRegionForMinLat:minLatitude minLong:minLongitude maxLat:maxLatitude maxLong:maxLongitude];
}


-(void) setMapRegionForMinLat:(double)minLatitude minLong:(double)minLongitude maxLat:(double)maxLatitude maxLong:(double)maxLongitude {

    // pad our map by 10% around the farthest annotations

    // we'll make sure that our minimum vertical span is about a kilometer
    // there are ~111km to a degree of latitude. regionThatFits will take care of
    // longitude, which is more complicated, anyway.

    MKCoordinateRegion region;
    region.center.latitude = (minLatitude + maxLatitude) / 2;
    region.center.longitude = (minLongitude + maxLongitude) / 2;

    region.span.latitudeDelta = (maxLatitude - minLatitude) * MAP_PADDING;

    region.span.latitudeDelta = (region.span.latitudeDelta < MINIMUM_VISIBLE_LATITUDE)
    ? MINIMUM_VISIBLE_LATITUDE
    : region.span.latitudeDelta;

    region.span.longitudeDelta = (maxLongitude - minLongitude) * MAP_PADDING;

    MKCoordinateRegion scaledRegion = [regionsMapView regionThatFits:region];
    [regionsMapView setRegion:scaledRegion animated:YES];

}