Swift - 根据从Firebase DB提取的数据的最近位置进行排序 [英] Swift - Sorting by Nearest Location from Data pulled from Firebase DB

问题描述

我试图从我的firebase后端检索数据 - 每个条目都有一个用户名lat和long。从查看其他的stackoverflow问题，我看到CoreLocation应该按照距离我们尝试使用的距离（或者距离（from :)）的方法进行排序。它似乎没有按预期工作。

 导入UIKit 
导入Firebase 
导入FirebaseDatabase 
导入MapKit 
导入CoreLocation 
 
类RequestVC：UITableViewController，CLLocationManagerDelegate {
 
 var locationManager = CLLocationManager（）
 var sellerUserNames = [String] （）
 var requestLocations = [CLLocationCoordinate2D]（）
 
 override func prepare（for segue：UIStoryboardSegue，sender：Any？）{
 if segue.identifier ==backToMain {
 self.navigationController？.navigationBar.isHidden = true 
} 
} 
 
覆盖func viewDidLoad（）{
 super.viewDidLoad（）
 
 locationManager.delegate = self 
 locationManager.desiredAccuracy = kCLLocationAccuracyBest 
 locationManager.requestWhenInUseAuthorization（）
 locationManager.startUpdatingLocation（）
 
 let databaseRef = FIRD观察（FIRDataEventType.childAdded，其中：{（FIRDataSnapshot）in 
 
如果let data = FIRDataSnapshot.value如？ NSDictionary {
如果让name = data [Constants.NAME] as？字符串{
如果让lat = data [纬度]为？ Double {
如果让long = data [longitude]为？ Double {
 
 print（\（self.sellerUserNames）Location：Latitude：\（lat），Longitude：\（long））
 
 self.sellerUserNames .append（name）
 self.requestLocations.append（CLLocationCoordinate2D（latitude：lat，longitude：long））
 
 self.tableView.reloadData（）
 
} 
 
 
 
 
 
 $ b func locationManager（_ manager：CLLocationManager，didUpdateLocations locations：[CLLocation]）{ 
} 
 
覆盖func numberOfSections（在tableView：UITableView中） - > Int {
 return 1 
} 
 
覆盖func tableView（_ tableView：UITableView，numberOfRowsInSection section：Int） - > Int {
 return sellerUserNames.count 
} 
 
 
覆盖func tableView（_ tableView：UITableView，cellForRowAt indexPath：IndexPath） - > UITableViewCell {
 
 let cell = tableView.dequeueReusableCell（withIdentifier：cell，for：indexPath）
 let location = locationManager.location？.coordinate 
 
 let buyerLocation = CLLocation（latitude：（location？.latitude）！，longitude：（location？.longitude）！）
 let sellerLocation = CLLocation（纬度：requestLocations [indexPath.row] .latitude，longitude：requestLocations [indexPath.row ] .longitude）
 
 let distance = buyerLocation.distance（from：sellerLocation）/ 1000 
 
 roundDistance = round（距离* 100）/ 100 
 
 let distanceInMiles = roundedDistance * 0.621 
 let roundedDistanceInMiles = round（distanceInMiles * 1000）/ 1000 
 
 
 cell.textLabel？.text = sellerUserNames [indexPath.row] + -  \（roundedDistanceInMiles）miles away
 
 return cell 
} 
} 
  

解决方案

你可以尝试使 GeoFire 正常工作。它不适用于cocoapods，虽然有解决方法。

I am trying to retrieve data from my firebase backend - Each entry has a username, lat and long. From looking at other stackoverflow questions, I see that CoreLocation is supposed to sort by nearest location with it's distancefrom (or rather, distance(from:)) method, which I tried to use. It doesn't seem to be working as intended. I'm wondering what I'm doing wrong.

import UIKit
import Firebase
import FirebaseDatabase
import MapKit
import CoreLocation

class RequestVC: UITableViewController, CLLocationManagerDelegate {

    var locationManager = CLLocationManager()
    var sellerUserNames = [String]()
    var requestLocations = [CLLocationCoordinate2D]()

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "backToMain" {
            self.navigationController?.navigationBar.isHidden = true
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.requestWhenInUseAuthorization()
        locationManager.startUpdatingLocation()

        let databaseRef = FIRDatabase.database().reference()
        databaseRef.child("Sell_Request").observe(FIRDataEventType.childAdded, with: { (FIRDataSnapshot) in

            if let data = FIRDataSnapshot.value as? NSDictionary {
                if let name = data[Constants.NAME] as? String {
                    if let lat = data["latitude"] as? Double {
                        if let long = data["longitude"] as? Double {

                            print("\(self.sellerUserNames) Location: Latitude: \(lat), Longitude: \(long)")

                            self.sellerUserNames.append(name)
                            self.requestLocations.append(CLLocationCoordinate2D(latitude: lat, longitude: long))

                            self.tableView.reloadData()

                        }
                    }
                }
            }
        })
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return sellerUserNames.count
    }


    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        let location = locationManager.location?.coordinate

        let buyerLocation = CLLocation(latitude: (location?.latitude)!, longitude: (location?.longitude)!)
        let sellerLocation = CLLocation(latitude: requestLocations[indexPath.row].latitude, longitude: requestLocations[indexPath.row].longitude)

        let distance = buyerLocation.distance(from: sellerLocation) / 1000

        let roundedDistance = round(distance * 100) / 100

        let distanceInMiles = roundedDistance * 0.621
        let roundedDistanceInMiles = round(distanceInMiles * 1000) / 1000


        cell.textLabel?.text = sellerUserNames[indexPath.row] + " - \(roundedDistanceInMiles) miles away"

        return cell
    }
}

解决方案

You could try do make GeoFire work. It doesn't work with cocoapods, though there are workarounds.

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