使用Firebase的geoFire .getLocation需要观察者在发生更改时进行监控，Swift

import Firebase
import GeoFire

let ref = Database.database().reference()

let geoFire = GeoFire(firebaseRef: ref.child("locations"))

let location = CLLocation(latitude: 37.7853889, longitude: -122.4056973)
let observer = geoFire.getLocationForKey("locationKey", withCallback: { (location, error) in
    if let error = error {
        print("获取位置失败：\(error.localizedDescription)")
    } else if let location = location {
        print("获取到位置：\(location.coordinate.latitude), \(location.coordinate.longitude)")
    } else {
        print("位置不存在")
    }
})

observer?.observe(.keyEntered, with: { (key, location) in
    print("位置发生变化：\(key) - \(location.coordinate.latitude), \(location.coordinate.longitude)")
})