ios 定位 MKMapView 以一次显示多个注释

Positioning MKMapView to show multiple annotations at once

提问by jbrennan

I've got several annotations I want to add to my MKMapView (it could 0-n items, where n is generally around 5). I can add the annotations fine, but I want to resize the map to fit all annotations onscreen at once, and I'm not sure how to do this.

我有几个注释要添加到我的 MKMapView（它可以是 0-n 个项目，其中 n 通常约为 5）。我可以很好地添加注释，但我想调整地图的大小以一次适合屏幕上的所有注释，但我不确定如何执行此操作。

I've been looking at -regionThatFits:but I'm not quite sure what to do with it. I'll post some code to show what I've got so far. I think this should be a generally straightforward task but I'm feeling a bit overwhelmed with MapKit so far.

我一直在看，-regionThatFits:但我不太确定如何处理它。我会发布一些代码来展示我到目前为止所得到的。我认为这通常应该是一项简单的任务，但到目前为止，我对 MapKit 感到有些不知所措。

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

location = newLocation.coordinate;
//One location is obtained.. just zoom to that location

MKCoordinateRegion region;
region.center = location;

//Set Zoom level using Span
MKCoordinateSpan span;
span.latitudeDelta = 0.015;
span.longitudeDelta = 0.015;
region.span = span;
// Set the region here... but I want this to be a dynamic size
// Obviously this should be set after I've added my annotations
[mapView setRegion:region animated:YES];

// Test data, using these as annotations for now
NSArray *arr = [NSArray arrayWithObjects:@"one", @"two", @"three", @"four", nil];
float ex = 0.01;
for (NSString *s in arr) {
    JBAnnotation *placemark = [[JBAnnotation alloc] initWithLat:(location.latitude + ex) lon:location.longitude];
    [mapView addAnnotation:placemark];
    ex = ex + 0.005;
}
    // What do I do here?
    [mapView setRegion:[mapView regionThatFits:region] animated:YES];
}

Notice, this all happens as I receive a location update... I don't know if that's an appropriate place to do this. If not, where would be a better place? -viewDidLoad?

请注意，这一切都是在我收到位置更新时发生的……我不知道这是否适合执行此操作。如果没有，哪里会更好？-viewDidLoad?

Thanks in advance.

提前致谢。

采纳答案by Code Commander

As of iOS7 you can use showAnnotations:animated:

从 iOS7 开始，您可以使用showAnnotations:animated：

[mapView showAnnotations:annotations animated:YES];

回答by Mustafa

The linkposted by Jim is now dead, but i was able to find the code (which I had bookmarked somewhere). Hope this helps.

Jim 发布的链接现已失效，但我能够找到代码（我已在某处添加了书签）。希望这可以帮助。

- (void)zoomToFitMapAnnotations:(MKMapView *)mapView { 
    if ([mapView.annotations count] == 0) return; 

    CLLocationCoordinate2D topLeftCoord; 
    topLeftCoord.latitude = -90; 
    topLeftCoord.longitude = 180; 

    CLLocationCoordinate2D bottomRightCoord; 
    bottomRightCoord.latitude = 90; 
    bottomRightCoord.longitude = -180; 

    for(id<MKAnnotation> annotation in mapView.annotations) { 
        topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude); 
        topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude); 
        bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude); 
        bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude); 
    } 

    MKCoordinateRegion region; 
    region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5; 
    region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;      

    // Add a little extra space on the sides
    region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1;
    region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1; 

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

回答by me2

Why so complicated?

为什么这么复杂？

MKCoordinateRegion coordinateRegionForCoordinates(CLLocationCoordinate2D *coords, NSUInteger coordCount) {
    MKMapRect r = MKMapRectNull;
    for (NSUInteger i=0; i < coordCount; ++i) {
        MKMapPoint p = MKMapPointForCoordinate(coords[i]);
        r = MKMapRectUnion(r, MKMapRectMake(p.x, p.y, 0, 0));
    }
    return MKCoordinateRegionForMapRect(r);
}

回答by Donald Byrd

I have done something similiar to this to zoom out (or in) to an area that included a point annotation and the current location. You could expand this by looping through your annotations.

我已经做了一些类似的事情来缩小（或放大）到一个包含点注释和当前位置的区域。您可以通过循环注释来扩展它。

The basic steps are:

基本步骤是：

• Calculate the min lat/long
  
• Calculate the max lat/long
  
• Create CLLocation objects for these two points
  
• Calculate distance between points
  
• Create region using center point between points and distance converted to degrees
  
• Pass region into MapView to adjust
  
• Use adjusted region to set MapView region
  

• 计算最小纬度/经度
  
• 计算最大纬度/经度
  
• 为这两个点创建 CLLocation 对象
  
• 计算点之间的距离
  
• 使用点之间的中心点和转换为度数的距离创建区域
  
• 将区域传入 MapView 进行调整
  
• 使用调整区域设置 MapView 区域
  

    -(IBAction)zoomOut:(id)sender {

        CLLocationCoordinate2D southWest = _newLocation.coordinate;
        CLLocationCoordinate2D northEast = southWest;

        southWest.latitude = MIN(southWest.latitude, _annotation.coordinate.latitude);
        southWest.longitude = MIN(southWest.longitude, _annotation.coordinate.longitude);

        northEast.latitude = MAX(northEast.latitude, _annotation.coordinate.latitude);
        northEast.longitude = MAX(northEast.longitude, _annotation.coordinate.longitude);

        CLLocation *locSouthWest = [[CLLocation alloc] initWithLatitude:southWest.latitude longitude:southWest.longitude];
        CLLocation *locNorthEast = [[CLLocation alloc] initWithLatitude:northEast.latitude longitude:northEast.longitude];

        // This is a diag distance (if you wanted tighter you could do NE-NW or NE-SE)
        CLLocationDistance meters = [locSouthWest getDistanceFrom:locNorthEast];

        MKCoordinateRegion region;
        region.center.latitude = (southWest.latitude + northEast.latitude) / 2.0;
        region.center.longitude = (southWest.longitude + northEast.longitude) / 2.0;
        region.span.latitudeDelta = meters / 111319.5;
        region.span.longitudeDelta = 0.0;

        _savedRegion = [_mapView regionThatFits:region];
        [_mapView setRegion:_savedRegion animated:YES];

        [locSouthWest release];
        [locNorthEast release];
    }

回答by PKCLsoft

I have a different answer. I was going to do implement the zoom-to-fit algorithm myself, but i figured that Apple musthave a way to do what we wanted without so much work. Using the API doco quickly showed that I could use MKPolygon to do what was needed:

我有不同的答案。我打算自己实现缩放以适应算法，但我认为 Apple必须有一种方法可以在没有这么多工作的情况下做我们想做的事情。使用 API doco 很快表明我可以使用 MKPolygon 来做需要的事情：

/* this simply adds a single pin and zooms in on it nicely */
- (void) zoomToAnnotation:(MapAnnotation*)annotation {
    MKCoordinateSpan span = {0.027, 0.027};
    MKCoordinateRegion region = {[annotation coordinate], span};
    [mapView setRegion:region animated:YES];
}

/* This returns a rectangle bounding all of the pins within the supplied
   array */
- (MKMapRect) getMapRectUsingAnnotations:(NSArray*)theAnnotations {
    MKMapPoint points[[theAnnotations count]];

    for (int i = 0; i < [theAnnotations count]; i++) {
        MapAnnotation *annotation = [theAnnotations objectAtIndex:i];
        points[i] = MKMapPointForCoordinate(annotation.coordinate);
    }

    MKPolygon *poly = [MKPolygon polygonWithPoints:points count:[theAnnotations count]];

    return [poly boundingMapRect];
}

/* this adds the provided annotation to the mapview object, zooming 
   as appropriate */
- (void) addMapAnnotationToMapView:(MapAnnotation*)annotation {
    if ([annotations count] == 1) {
        // If there is only one annotation then zoom into it.
        [self zoomToAnnotation:annotation];
    } else {
        // If there are several, then the default behaviour is to show all of them
        //
        MKCoordinateRegion region = MKCoordinateRegionForMapRect([self getMapRectUsingAnnotations:annotations]);

        if (region.span.latitudeDelta < 0.027) {
            region.span.latitudeDelta = 0.027;
        }

        if (region.span.longitudeDelta < 0.027) {
            region.span.longitudeDelta = 0.027;
        }
        [mapView setRegion:region];
    }

    [mapView addAnnotation:annotation];
    [mapView selectAnnotation:annotation animated:YES];
}

Hope this helps.

希望这可以帮助。

回答by Manish Ahuja

you can also do it this way..

你也可以这样做..

// Position the map so that all overlays and annotations are visible on screen.
MKMapRect regionToDisplay = [self mapRectForAnnotations:annotationsToDisplay];
if (!MKMapRectIsNull(regionToDisplay)) myMapView.visibleMapRect = regionToDisplay;

- (MKMapRect) mapRectForAnnotations:(NSArray*)annotationsArray
{
    MKMapRect mapRect = MKMapRectNull;

    //annotations is an array with all the annotations I want to display on the map
    for (id<MKAnnotation> annotation in annotations) { 

        MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
        MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 0);

        if (MKMapRectIsNull(mapRect)) 
        {
            mapRect = pointRect;
        } else 
        {
            mapRect = MKMapRectUnion(mapRect, pointRect);
        }
    }

     return mapRect;
}

回答by nh32rg

Based on the information and suggestions from everyone I came up with the following. Thanks for everyone in this discussion for contributing :) This would go in the view Controller that contains the mapView.

根据大家的信息和建议，我想出了以下内容。感谢这个讨论中的每个人的贡献:) 这将进入包含 mapView 的视图控制器。

- (void)zoomToFitMapAnnotations { 

if ([self.mapView.annotations count] == 0) return; 

int i = 0;
MKMapPoint points[[self.mapView.annotations count]];

//build array of annotation points
for (id<MKAnnotation> annotation in [self.mapView annotations])
        points[i++] = MKMapPointForCoordinate(annotation.coordinate);

MKPolygon *poly = [MKPolygon polygonWithPoints:points count:i];

[self.mapView setRegion:MKCoordinateRegionForMapRect([poly boundingMapRect]) animated:YES]; 
}

回答by jacobsimeon

In my case, I am starting with CLLocation objects and creating annotations for each of them.
I only need to place two annotations, so I have a simple approach to building the array of points, but it could easily be expanded to build an array with an arbitrary length given a set of CLLocations.

就我而言，我从 CLLocation 对象开始并为每个对象创建注释。
我只需要放置两个注释，所以我有一个简单的方法来构建点数组，但是可以很容易地扩展它以构建一个给定一组 CLLocations 的任意长度的数组。

Here's my implementation (doesn't require creating MKMapPoints):

这是我的实现（不需要创建 MKMapPoints）：

//start with a couple of locations
CLLocation *storeLocation = store.address.location.clLocation;
CLLocation *userLocation = [LBLocationController sharedController].currentLocation;

//build an array of points however you want
CLLocationCoordinate2D points[2] = {storeLocation.coordinate, userLocation.coordinate};

//the magic part
MKPolygon *poly = [MKPolygon polygonWithCoordinates:points count:2];
[self.mapView setRegion:MKCoordinateRegionForMapRect([poly boundingMapRect])];

回答by Lindsay Thurmond

Using Swift, a polygon, and some extra padding I used the following:

使用 Swift、多边形和一些额外的填充，我使用了以下内容：

func zoomToFit() {
    var allLocations:[CLLocationCoordinate2D] = [
        CLLocationCoordinate2D(latitude: 32.768805, longitude: -117.167119),
        CLLocationCoordinate2D(latitude: 32.770480, longitude: -117.148385),
        CLLocationCoordinate2D(latitude: 32.869675, longitude: -117.212929)
    ]

    var poly:MKPolygon = MKPolygon(coordinates: &allLocations, count: allLocations.count)

    self.mapView.setVisibleMapRect(poly.boundingMapRect, edgePadding: UIEdgeInsetsMake(40.0, 40.0, 40.0, 40.0), animated: false)
}

回答by Paul Lehn

I know this is an old question but, if you want to display all the annotations ALREADY ON the map use this:

我知道这是一个老问题，但是，如果您想在地图上显示所有注释，请使用以下命令：

 mapView.showAnnotations(mapView.annotations, animated: true)