从点+半径/距离（iPhone SDK）的MKPolygon

Question

我怎样才能从CLLocationCoordinate2D（中心点）和CLLocationDistance（半径 - 绿线）计算MKPolygon？

我想对与给定半径的地图，以显示一个矩形（蓝线）

感谢

Answer 1

我适于从@Cyril戈德弗鲁瓦答案和从How to make the union between two MKCoordinateRegion

- (MKMapRect) mapRectForCoordinateRegion:(MKCoordinateRegion)coordinateRegion { 
    CLLocationCoordinate2D topLeftCoordinate = CLLocationCoordinate2DMake(coordinateRegion.center.latitude + (coordinateRegion.span.latitudeDelta/2.0), coordinateRegion.center.longitude - (coordinateRegion.span.longitudeDelta/2.0)); 

    MKMapPoint topLeftMapPoint = MKMapPointForCoordinate(topLeftCoordinate); 

    CLLocationCoordinate2D bottomRightCoordinate = CLLocationCoordinate2DMake(coordinateRegion.center.latitude - (coordinateRegion.span.latitudeDelta/2.0), coordinateRegion.center.longitude + (coordinateRegion.span.longitudeDelta/2.0)); 

    MKMapPoint bottomRightMapPoint = MKMapPointForCoordinate(bottomRightCoordinate); 

    MKMapRect mapRect = MKMapRectMake(topLeftMapPoint.x, topLeftMapPoint.y, fabs(bottomRightMapPoint.x - topLeftMapPoint.x), fabs(bottomRightMapPoint.y - topLeftMapPoint.y)); 

    return mapRect; 
} 

- (void) addSquareToMap:(CLLocation*)center withRadius:(float)radius{ 
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(center, radius*2, radius*2); 
    MKMapRect rect = [self mapRectForCoordinateRegion:region]; 

    MKMapPoint leftBottom = MKMapPointMake(MKMapRectGetMinX(rect), MKMapRectGetMinY(rect)); 
    MKMapPoint leftTop = MKMapPointMake(MKMapRectGetMinX(rect), MKMapRectGetMaxY(rect)); 
    MKMapPoint rightTop = MKMapPointMake(MKMapRectGetMaxX(rect), MKMapRectGetMaxY(rect)); 
    MKMapPoint rightBottom = MKMapPointMake(MKMapRectGetMaxX(rect), MKMapRectGetMinY(rect)); 

    MKMapPoint rect[4] = {leftBottom, leftTop, rightTop, rightBottom}; 

    MKPolygon *polygon = [MKPolygon polygonWithPoints:rect count:4]; 
    poly.title = @"Square"; 

    // Add it to the map 
    [map addOverlay:poly]; 
} 

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay{ 
    if ([overlay isKindOfClass:[MKPolygon class]]){ 
     MKPolygonView* aView = [[[MKPolygonView alloc] initWithPolygon:(MKPolygon*)overlay] autorelease]; 

     aView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.15]; 
     aView.strokeColor = [[UIColor redColor] colorWithAlphaComponent:0.7]; 
     aView.lineWidth = 3; 

     return aView; 
    } 

return nil; 
} 

Answer 2

通常矩形没有一个半径，圆了。所以我想你的意思是“方形的一面”，因为你实际上想画一个正方形？

您需要计算您的方形角落的4个坐标。

- (void) addSquareToMap:(CLLocation*)center withRadius:(float)radius{ 
    // Create a C array of size 4 
    CLLocationCoordinate2D points[4]; 

    //Fill the array with the four corners (center - radius in each of four directions) 
    points[0] = CLLocationCoordinate2DMake(center.coordinate.latitude-radius, coord.longitude-radius); 
    points[1] = CLLocationCoordinate2DMake(center.coordinate.latitude+radius, coord.longitude-radius); 
    points[2] = CLLocationCoordinate2DMake(center.coordinate.latitude+radius, coord.longitude+radius); 
    points[3] = CLLocationCoordinate2DMake(center.coordinate.latitude-radius, coord.longitude+radius); 

    //Create the polygon 
    MKPolygon* poly = [MKPolygon polygonWithCoordinates:points count:4]; 
    poly.title = @"Square"; 

    // Add it to the map 
    [map addOverlay:poly]; 
} 

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay{ 
    if ([overlay isKindOfClass:[MKPolygon class]]){ 
     MKPolygonView* aView = [[[MKPolygonView alloc] initWithPolygon:(MKPolygon*)overlay] autorelease]; 

     aView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.15]; 
     aView.strokeColor = [[UIColor redColor] colorWithAlphaComponent:0.7]; 
     aView.lineWidth = 3; 

     return aView; 
    } 

return nil; 

}

编辑：对不起，我误解你的问题的“米”部分，所以这里是一个更简单的答案。

- (void) addSquareToMap:(CLLocation*)center withRadius:(float)radius{ 
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(center.coordinate, radius*2, radius*2); 

    CLLocationCoordinate2D points[4]; 

    //Fill the array with the four corners (center - span/2 in each of four directions) 
    points[0] = CLLocationCoordinate2DMake(region.center.latitude - region.span.latitudeDelta/2, region.center.longitude - region.span.longitudeDelta/2); 
    points[1] = CLLocationCoordinate2DMake(region.center.latitude + region.span.latitudeDelta/2, region.center.longitude - region.span.longitudeDelta/2); 
    points[2] = CLLocationCoordinate2DMake(region.center.latitude + region.span.latitudeDelta/2, region.center.longitude + region.span.longitudeDelta/2); 
    points[3] = CLLocationCoordinate2DMake(region.center.latitude - region.span.latitudeDelta/2, region.center.longitude + region.span.longitudeDelta/2); 

    MKPolygon *polygon = [MKPolygon polygonWithCoordinates:points count:4]; 
    polygon.title = @"Square"; 

    // Add it to the map 
    [self.mapView addOverlay:polygon]; 
} 

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay{ 
    if ([overlay isKindOfClass:[MKPolygon class]]){ 
     MKPolygonView* aView = [[[MKPolygonView alloc] initWithPolygon:(MKPolygon*)overlay] autorelease]; 

     aView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.15]; 
     aView.strokeColor = [[UIColor redColor] colorWithAlphaComponent:0.7]; 
     aView.lineWidth = 3; 

     return aView; 
    } 

    return nil; 
} 

可以很容易地通过用替换allAction方法与MapCallouts示例测试：

- (IBAction)allAction:(id)sender{ 
    //CLLocationCoordinate2D SF = CLLocationCoordinate2DMake(37.786996, -122.440100) ; 
    CLLocation *center = [[CLLocation alloc] initWithLatitude:37.786996 longitude:-122.440100]; 
    [self addSquareToMap:center withRadius:1000]; 
}