按距离排序 Geofire 结果

Question

I've been experimenting with Geofire for iOS but can't seem to find any way of returning the distance from the search position in a circle query. The GFQueryResultBlock only returns the key and position. Am I right in assuming that I have to calculate the distance myself?

Let's say I am making a nearby restaurant app with Firebase, and want to display the 20 closest restaurants to the user, ordered by how close they are. I could create a circle query and then increase the search radius via a loop until I find 20 restaurants. Then calculate the distance for each one and sort them before displaying them to the user. Is this a reasonable approach, given that a large amount of work is being done in the app to structure the data (calculating distance & sorting)?

I've noticed that javascript Geofire queries return distance from the center, but I guess the iOS and android versions are different from this.

Answer 1

当您从Geofire查询时，相关结果会自动升序排列。所以为了获得距离，我只使用 distanceFromLocation 函数：这是我的代码：

func getGeoFirePlaces(){

    let geofireRef = FIRDatabase.database().reference().child("testForGeofire")
    let geoFire  = GeoFire(firebaseRef: geofireRef)
    //geoFireRef is pointing to a firebase reference where I previously set all  places' location 
    let userPosition = CLLocation(latitude: 32.0776067, longitude: 34.78912)
    let circleQuery = geoFire.queryAtLocation(userPosition, withRadius: 2)

    circleQuery.observeEventType(.KeyEntered, withBlock: { (key: String!, location: CLLocation!) in
        print("Key '\(key)' entered the search area and is at location '\(location)'")

        //getting distance of each Place return with the callBack
        let distanceFromUser = userPosition.distanceFromLocation(location)
        print(distanceFromUser)
    })

}

希望对您有所帮助！

按距离排序 Geofire 结果

Ordering Geofire results on Distance

ios

firebase

geofire

firebase-realtime-database