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I have a list (NSMutableArray) of latlong surrounding the Dhaka City region. Now want want to determine a provided lat long is in the Dhaka City Region.

My code is provided below: 

+(NSMutableArray*)getAvailableAddress {
    NSMutableArray* dhakaAvailableAreas=[[NSMutableArray alloc]init];
    NSDictionary *latLongDict = @{@"lat" : @(23.665217), @"long":@(90.456556)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710108), @"long":@(90.400022)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.707796), @"long":@(90.366647)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.744056), @"long":@(90.345334)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.751866), @"long":@(90.333149)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.768038), @"long":@(23.768038)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.774732), @"long":@(90.336199)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.796483), @"long":@(90.338031)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.833850), @"long":@(90.339256)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.853928), @"long":@(90.342309)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.867869), @"long":@(90.351460)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.887389), @"long":@(90.358176)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.899096), @"long":@(90.380142)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.882914), @"long":@(90.394773)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.886806), @"long":@(90.417956)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.899729), @"long":@(90.440122)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.895324), @"long":@(90.456267)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.861075), @"long":@(90.475134)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.840659), @"long":@(90.473056)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.828086), @"long":@(90.486782)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.793225), @"long":@(90.480572)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.782239), @"long":@(90.470264)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.770608), @"long":@(90.482614)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.753955), @"long":@(90.488093)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.747045), @"long":@(90.486714)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.742954), @"long":@(90.494262)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.732360), @"long":@(90.493535)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.717059), @"long":@(90.500136)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710997), @"long":@(90.508137)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710997), @"long":@(90.508137)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.693175), @"long":@(90.480623)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.672433), @"long":@(90.468799)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.667661), @"long":@(90.458352)};
    [dhakaAvailableAreas addObject:latLongDict];

    return dhakaAvailableAreas;

}

Now if I provide a lat long for example lat=23.665219 and long=90400023 How can I determine the lat long is in the Dhaka City Region

Thanks in advance.

Mahboob Nur
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  • You need to show what you've tried, rather than just give the data. To help you try look at [this question](https://stackoverflow.com/questions/217578/how-can-i-determine-whether-a-2d-point-is-within-a-polygon). HTH – CRD Mar 31 '19 at 15:18

3 Answers3

1

Your task, as it seems to me, is Point-in-polygon (PIP) problem [https://en.wikipedia.org/wiki/Point_in_polygon]

To achieve what you want you could use "Ray casting algorithm"

I made pretty quick implementation of this algorithm, so you could start from this

@implementation PointInRegion

+(NSMutableArray*)getAvailableAddress {
    NSMutableArray* dhakaAvailableAreas=[[NSMutableArray alloc]init];
    NSDictionary *latLongDict = @{@"lat" : @(23.665217), @"long":@(90.456556)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710108), @"long":@(90.400022)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.707796), @"long":@(90.366647)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.744056), @"long":@(90.345334)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.751866), @"long":@(90.333149)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.768038), @"long":@(23.768038)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.774732), @"long":@(90.336199)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.796483), @"long":@(90.338031)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.833850), @"long":@(90.339256)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.853928), @"long":@(90.342309)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.867869), @"long":@(90.351460)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.887389), @"long":@(90.358176)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.899096), @"long":@(90.380142)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.882914), @"long":@(90.394773)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.886806), @"long":@(90.417956)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.899729), @"long":@(90.440122)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.895324), @"long":@(90.456267)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.861075), @"long":@(90.475134)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.840659), @"long":@(90.473056)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.828086), @"long":@(90.486782)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.793225), @"long":@(90.480572)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.782239), @"long":@(90.470264)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.770608), @"long":@(90.482614)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.753955), @"long":@(90.488093)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.747045), @"long":@(90.486714)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.742954), @"long":@(90.494262)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.732360), @"long":@(90.493535)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.717059), @"long":@(90.500136)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710997), @"long":@(90.508137)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.710997), @"long":@(90.508137)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.693175), @"long":@(90.480623)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.672433), @"long":@(90.468799)};
    [dhakaAvailableAreas addObject:latLongDict];
    latLongDict = @{@"lat" : @(23.667661), @"long":@(90.458352)};
    [dhakaAvailableAreas addObject:latLongDict];

    return dhakaAvailableAreas;
}

+ (BOOL)checkIfPoint:(CLLocationCoordinate2D)point inRegion:(NSArray<NSDictionary<NSString *, NSNumber *> *> *)region {
    int intersectionsCount = 0;
    for (int i = 1; i < region.count; i++) {
        double lat1 = region[i - 1][@"lat"].doubleValue;
        double long1 = region[i - 1][@"long"].doubleValue;
        double lat2 = region[i][@"lat"].doubleValue;
        double long2 = region[i][@"lat"].doubleValue;

        CLLocationCoordinate2D point1;
        point1.latitude = lat1;
        point1.longitude = long1;

        CLLocationCoordinate2D point2;
        point2.latitude = lat2;
        point2.longitude = long2;


        BOOL intersects = [PointInRegion checkIfHorizontalVectorFromPoint:point intersectsEdge:point1 edgePoint2:point2];
        if (intersects) {
            intersectionsCount++;
        }
    }

    return intersectionsCount % 2 > 0;
}

+ (BOOL)checkIfHorizontalVectorFromPoint:(CLLocationCoordinate2D)point intersectsEdge:(CLLocationCoordinate2D)edgePoint1 edgePoint2:(CLLocationCoordinate2D)edgePoint2 {
    double lat = point.latitude;
    double longitude = point.longitude;

    double lat1 = edgePoint1.latitude;
    double long1 = edgePoint1.longitude;
    double lat2 = edgePoint2.latitude;
    double long2 = edgePoint2.longitude;

    if ( lat1 - lat2 == 0 ) {
        // Horizontal line
        return NO;
    }

    double x = ((long1 - long2) * lat - (long1 * lat2 - long2 * lat1)) / (lat1 - lat2);
    if (longitude < x) {
        // Intersection point lies not on the vector
        return NO;
    }
    double diff1 = lat1 - lat;
    double diff2 = lat2 - lat;
    if (fmax(diff1, diff2) > 0 && fmin(diff1, diff2) < 0) {
        // Points lie in different sides
        return YES;
    }
    return NO;
}

@end

You can use the code like this:

CLLocationCoordinate2D point;
point.latitude = 23.665219;
point.longitude = 90.400023;
[PointInRegion checkIfPoint:(CLLocationCoordinate2D)point inRegion: 
[PointInRegion getAvailableAddress]];
Serj Kultenko
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  • PointInRegion is a class in which I included al the code. Just call next code: CLLocationCoordinate2D point; point.latitude = 23.665219; point.longitude = 90.400023; [PointInRegion checkIfPoint:(CLLocationCoordinate2D)point inRegion: [PointInRegion getAvailableAddress]]; – Serj Kultenko Apr 01 '19 at 06:28
0

Reverse-geocoding requests take a latitude and longitude value and find a user-readable address. You will need to feed your lat, lon to a reverse-geocoder to determine the address (the country, city part) and determine if it lies within the city of your interest.

You can use the CLGeocoder API to achieve what you want: https://developer.apple.com/documentation/corelocation/clgeocoder Check out the discussions here for a similar question: How to check if lat long is in the city limits

Google's geocoding API here: https://developers.google.com/maps/documentation/geocoding/intro

Raunak
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0

Finally I get a sollution using GMSGeometryContainsLocation, and it works more accurately and fine.

if (GMSGeometryContainsLocation(locationPoint, polygonPath, YES)) {
    NSLog(@"locationPoint is in polygonPath.");
} else {
    NSLog(@"locationPoint is NOT in polygonPath.");
}
Mahboob Nur
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