swift - 无法从Firebase数据库Swift 4中获取数据

我只是想显示用户离这个位置有多远，但似乎无法将任何内容打印到我的控制台上。如果我将代码放在viewDidLoad中并手动放在“postLocations”的坐标中
我得到了距离，但我似乎无法得到任何打印与我目前的代码。

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    let userLocation: CLLocation = locations[0] as CLLocation

    let ref = Database.database().reference().child("posts")
    ref.observeSingleEvent(of: .value, with: { (snapshot) in

        guard let dictionary = snapshot.value as? [String: AnyObject] else { return }

        guard let latitude = dictionary["latitude"] as? Double else { return }
        guard let longitude = dictionary["longitude"] as? Double else { return }

        let currentLocation = Coordinate(long: userLocation.coordinate.longitude, lat: userLocation.coordinate.latitude)
        let postLocations = Coordinate(long: longitude, lat: latitude)

        if currentLocation.distance(to: postLocations) <= 100 {
            print("You are \(currentLocation.distance(to: postLocations)) away from posts")
        } else {
            print("No posts in area")
        }

    }) { (error) in
        print("There was an error getting posts", error)
    }

    }

最佳答案

在viewDidLoad中尝试此代码，并检查控制台中的print语句是否已打印纬度和经度。

func fetchUserLocation() {
     let ref = Database.database().reference().child("posts")
     ref.observeSingleEvent(of: .value, with: { (snapshot) in
     guard let dictionary = snapshot.value as? [String: AnyObject] else { return }
     guard let latitude = dictionary["latitude"] as? String else { return }
     guard let longitude = dictionary["longitude"] as? String else { return }
     print("lat: \(latitude), lon: \(longitude)")
   }) { (error) in
    print("There was an error getting posts", error)
  }
}

关于swift - 无法从Firebase数据库Swift 4中获取数据，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53147335/