func geoQuery()

in firestore/swift/firestore-smoketest/SolutionGeoPointViewController.swift [57:104]
16 lines of code
2 McCabe index (conditional complexity)

    func geoQuery() {
        // [START fs_geo_query_hashes]
        // Find cities within 50km of London
        let center = CLLocationCoordinate2D(latitude: 51.5074, longitude: 0.1278)
        let radiusInM: Double = 50 * 1000

        // 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: radiusInM)
        let queries = queryBounds.map { bound -> Query in
            return db.collection("cities")
                .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
            }

            for document in documents {
                let lat = document.data()["lat"] as? Double ?? 0
                let lng = document.data()["lng"] as? Double ?? 0
                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)
                if distance <= radiusInM {
                    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)
        }
        // [END fs_geo_query_hashes]
    }