GeoHash Queries in Firebase with Swift

Question

I'm super excited about the new geo query feature available in Firebase. I'm trying out the 'GeoFire/Utils' pod recently made available. I set up a test iOS app and here is the repo . I left the rules open if anyone wants to clone and try. My Firestore document looks like this.

date : January 29, 2021 at 1:29:00 PM UTC-8
geohash:"9mupwu3mkc"
id:"13101C7F-D7FF-4141-BC5A-76602173C096"
lat:33.6863622
lng:-117.8264411
ownerAddress:"1 Civic Center Plaza, Irvine CA 92606"

I am using the samplecode from firebase. Here is the call to firebase

func getallDocs(radius: Double) {
    // Find pickups within 50km of Basecamp
    let center = CLLocationCoordinate2D(latitude: 33.9742268, longitude: -118.3947792)
    let radiusInKilometers: Double = radius

    // Each item in 'bounds' represents a startAt/endAt pair. We have to issue
    // a separate query for each pair. There can be up to 9 pairs of bounds
    // depending on overlap, but in most cases there are 4.
    let queryBounds = GFUtils.queryBounds(forLocation: center,
                                          withRadius: radiusInKilometers)
    let queries = queryBounds.compactMap { (any) -> Query? in
        guard let bound = any as? GFGeoQueryBounds else { return nil }
        return db.collection("pickups")
            .order(by: "geohash")
            .start(at: [bound.startValue])
            .end(at: [bound.endValue])
    }

    var matchingDocs = [QueryDocumentSnapshot]()
    // Collect all the query results together into a single list
    func getDocumentsCompletion(snapshot: QuerySnapshot?, error: Error?) -> () {
        guard let documents = snapshot?.documents else {
            print("Unable to fetch snapshot data. \(String(describing: error))")
            return
        }
        
        print("\nDocs: Count \(documents.count)")
        for document in documents {
            let lat = document.data()["lat"] as? Double ?? 0
            let lng = document.data()["lng"] as? Double ?? 0
            let ownerAddress = document.data()["ownerAddress"] as? String ?? "no address"
            let coordinates = CLLocation(latitude: lat, longitude: lng)
            let centerPoint = CLLocation(latitude: center.latitude, longitude: center.longitude)

            // We have to filter out a few false positives due to GeoHash accuracy, but
            // most will match
            let distance = GFUtils.distance(from: centerPoint, to: coordinates)
            print("ownerAddress: \(ownerAddress), distance: \(distance) \tlat: \(lat), \(lng)")
            if distance <= radiusInKilometers {
                matchingDocs.append(document)
            }
        }
    }

    // After all callbacks have executed, matchingDocs contains the result. Note that this
    // sample does not demonstrate how to wait on all callbacks to complete.
    for query in queries {
        query.getDocuments(completion: getDocumentsCompletion)
    }
    print("Docs: \(matchingDocs.count)")
}

My distances are way off. Here is an example of my output, the top one is my query center. And with a query radius of 100,000 km I still don't get all of my addresses in California.

Home Base: 7401 Sepluveda, Los Angeles CA 90045, distance: 0.0  lat: 33.9742268, -118.3947792
ownerAddress: 1204 Mira Mar Ave, Long Beach CA 90301, distance: 31295.135631869747  lat: 33.781846, -118.1473443
ownerAddress: 625 Fair Oaks, Pasadena CA 91030, distance: 27608.75410615904     lat: 34.1181627, -118.1510438

My question is why is my distance so much greater than what google maps / reality is?

Answer 1

firebaser here

From our chat in the comments it seems that the withRadius: value is actually in meters, despite what the documentation says.

This is clearly not working as documented, so I filed a to update the docs. That change is coming in here .

Answer 2

I'm super excited about the new geo query feature available in Firebase. I'm trying out the 'GeoFire/Utils' pod recently made available. I set up a test iOS app and here is the repo . I left the rules open if anyone wants to clone and try. My Firestore document looks like this.

date : January 29, 2021 at 1:29:00 PM UTC-8
geohash:"9mupwu3mkc"
id:"13101C7F-D7FF-4141-BC5A-76602173C096"
lat:33.6863622
lng:-117.8264411
ownerAddress:"1 Civic Center Plaza, Irvine CA 92606"

I am using the samplecode from firebase. Here is the call to firebase

func getallDocs(radius: Double) {
    // Find pickups within 50km of Basecamp
    let center = CLLocationCoordinate2D(latitude: 33.9742268, longitude: -118.3947792)
    let radiusInKilometers: Double = radius

    // Each item in 'bounds' represents a startAt/endAt pair. We have to issue
    // a separate query for each pair. There can be up to 9 pairs of bounds
    // depending on overlap, but in most cases there are 4.
    let queryBounds = GFUtils.queryBounds(forLocation: center,
                                          withRadius: radiusInKilometers)
    let queries = queryBounds.compactMap { (any) -> Query? in
        guard let bound = any as? GFGeoQueryBounds else { return nil }
        return db.collection("pickups")
            .order(by: "geohash")
            .start(at: [bound.startValue])
            .end(at: [bound.endValue])
    }

    var matchingDocs = [QueryDocumentSnapshot]()
    // Collect all the query results together into a single list
    func getDocumentsCompletion(snapshot: QuerySnapshot?, error: Error?) -> () {
        guard let documents = snapshot?.documents else {
            print("Unable to fetch snapshot data. \(String(describing: error))")
            return
        }
        
        print("\nDocs: Count \(documents.count)")
        for document in documents {
            let lat = document.data()["lat"] as? Double ?? 0
            let lng = document.data()["lng"] as? Double ?? 0
            let ownerAddress = document.data()["ownerAddress"] as? String ?? "no address"
            let coordinates = CLLocation(latitude: lat, longitude: lng)
            let centerPoint = CLLocation(latitude: center.latitude, longitude: center.longitude)

            // We have to filter out a few false positives due to GeoHash accuracy, but
            // most will match
            let distance = GFUtils.distance(from: centerPoint, to: coordinates)
            print("ownerAddress: \(ownerAddress), distance: \(distance) \tlat: \(lat), \(lng)")
            if distance <= radiusInKilometers {
                matchingDocs.append(document)
            }
        }
    }

    // After all callbacks have executed, matchingDocs contains the result. Note that this
    // sample does not demonstrate how to wait on all callbacks to complete.
    for query in queries {
        query.getDocuments(completion: getDocumentsCompletion)
    }
    print("Docs: \(matchingDocs.count)")
}

My distances are way off. Here is an example of my output, the top one is my query center. And with a query radius of 100,000 km I still don't get all of my addresses in California.

Home Base: 7401 Sepluveda, Los Angeles CA 90045, distance: 0.0  lat: 33.9742268, -118.3947792
ownerAddress: 1204 Mira Mar Ave, Long Beach CA 90301, distance: 31295.135631869747  lat: 33.781846, -118.1473443
ownerAddress: 625 Fair Oaks, Pasadena CA 91030, distance: 27608.75410615904     lat: 34.1181627, -118.1510438

My question is why is my distance so much greater than what google maps / reality is?