ios - 检查 CLLocation 是否处于形状中？

Question

我正在寻找一种方法来检测用户是在荷兰还是在比利时。我不想调用 API 或使用用户电话服务，所以一切都需要在本地完成，并且应该是简单快捷的小检查。我每秒都有用户的位置，并且想每分钟检查一次。

目标:
用户正在使用我们的应用程序旅行，我想在他/她到达比利时/荷兰时展示不同的 View 。

我从 http://www.diva-gis.org/datadown 中找到了两个形状文件与荷兰和比利时。这些文件非常小，现在我正在寻找一种方法来创建这个方法:

- (BOOL)isUserInNetherlands:(CLLocation)location;

应该检查位置是否在 shapefile 的内容中。

荷兰的 shapefile 如下所示:



我可以将 shapefile 转换为 sqlLite 数据库，但不知道下一步该做什么。

有任何想法吗？

Answer 1

一种方法是:

1)将shapefile转换为geoJson

2)在您的代码中加载geoJson文件数据。

3)从这些gps点创建多边形(注意:CountryDetectorController是我的 Controller 类)

+ (MKPolygon *)overlaysFromPolygons:(NSArray *)polygons title:(NSString *)title;
{
    NSMutableArray *interiorPolygons = [NSMutableArray arrayWithCapacity:[polygons count] - 1];
    for (int i = 1; i < [polygons count]; i++) {
        [interiorPolygons addObject:[CountryDetectorController polygonFromPoints:polygons[i] interiorPolygons:nil]];
    }

    MKPolygon *overlayPolygon = [CountryDetectorController polygonFromPoints:polygons[0] interiorPolygons:interiorPolygons];
    overlayPolygon.title = title;


    return overlayPolygon;
}

+ (MKPolygon *)polygonFromPoints:(NSArray *)points interiorPolygons:(NSArray *)polygons;
{
    NSInteger numberOfCoordinates = [points count];
    CLLocationCoordinate2D *polygonPoints = malloc(numberOfCoordinates * sizeof(CLLocationCoordinate2D));

    NSInteger index = 0;
    for (NSArray *pointArray in points) {
        polygonPoints[index] = CLLocationCoordinate2DMake([pointArray[1] floatValue], [pointArray[0] floatValue]);
        index++;
    }

    MKPolygon *polygon;

    if (polygons) {
        polygon = [MKPolygon polygonWithCoordinates:polygonPoints count:numberOfCoordinates interiorPolygons:polygons];
    } else {
        polygon = [MKPolygon polygonWithCoordinates:polygonPoints count:numberOfCoordinates];
    }
    free(polygonPoints);

    return polygon;
}

4)从多边形创建一个CGPath

+ (CGPathRef)pathForPolygon:(MKPolygon*)aPolygon;
{
    CGMutablePathRef mpr = CGPathCreateMutable();

    MKMapPoint *polygonPoints = aPolygon.points;
    size_t nCount = aPolygon.pointCount;

    for (int p = 0; p < nCount; p++)
    {
        MKMapPoint mp = polygonPoints[p];

        if (p == 0)
            CGPathMoveToPoint(mpr, NULL, mp.x, mp.y);
        else
            CGPathAddLineToPoint(mpr, NULL, mp.x, mp.y);
    }

    return mpr; //Keep in memory;
}

5) 检查坐标是否在 CGPath 中(pathsBelgium 是一个 NSValue 为 CGPaths 的数组)

- (void)checkCoordinate:(CLLocationCoordinate2D)coordinate;
{
    MKMapPoint mapPoint = MKMapPointForCoordinate(coordinate);
    CGPoint mapPointAsCGP = CGPointMake(mapPoint.x, mapPoint.y);

    BOOL userIsInBelgium = FALSE;
    for(NSValue *valuePathBE in pathsBelgium)
    {
        CGPathRef pathBe;
        [valuePathBE getValue:&pathBe];

        BOOL pointInBelgium = CGPathContainsPoint(pathBe, NULL, mapPointAsCGP, FALSE);
        if(pointInBelgium)
        {
            userIsInBelgium = TRUE;
            break;
        }
    }

    NSLog(@"User is in Belgium: %i", userIsInBelgium);
}