从Firebase检索数据并作为注释存储在地图上 [英] Retrieving data from Firebase and storing as annotations on a map

问题描述

我已经成功地将数据从我在视图控制器中创建的表单存储到Firebase数据库中，但是现在需要检索数据以在第二个视图控制器上的地图上显示为批注，但我不知道该怎么做在网上搜索并没有找到任何东西后，继续执行此任务.

I've successfully managed to store data to my Firebase database from a form I created in a view controller but now need to retrieve the data to display as annotations on a map on a second view controller but do not know how I should go about doing this task after searching and finding nothing online.

这是我的工作代码，可将我的数据成功保存到Firebase数据库:

Here is my working code that saves my data successfully to the Firebase database:

import UIKit
import CoreLocation
import Firebase

class AddSightingViewController: UIViewController {

    @IBOutlet weak var dateLabel: UILabel!
    @IBOutlet weak var timeLabel: UILabel!
    @IBOutlet weak var latitudeLabel: UILabel!
    @IBOutlet weak var longitudeLabel: UILabel!
    @IBOutlet weak var descriptionLabel: UITextView!

    var locManager = CLLocationManager()
    var currentLocation: CLLocation!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Set Date & Time

        let dateFormatter = DateFormatter()
        dateFormatter.dateStyle = .medium

        dateFormatter.setLocalizedDateFormatFromTemplate("EEEE, MMM d, yyyy") // // set template after setting locale

        let dateString = "\(dateFormatter.string(from: Date() as Date))"
        dateLabel.text = String(dateString)

        let timeFormatter = DateFormatter()
        timeFormatter.timeStyle = .medium

        timeFormatter.setLocalizedDateFormatFromTemplate("hhmm")

        let timeString = "\(timeFormatter.string(from: Date() as Date))"

        timeLabel.text = String(timeString)

        // Set Latitude & Longitude

        locManager.requestWhenInUseAuthorization()

        if (CLLocationManager.authorizationStatus() == CLAuthorizationStatus.authorizedWhenInUse ||
            CLLocationManager.authorizationStatus() == CLAuthorizationStatus.authorizedAlways){
            currentLocation = locManager.location
            self.latitudeLabel.text = String("\(currentLocation.coordinate.latitude)")
            self.longitudeLabel.text = String("\(currentLocation.coordinate.longitude)")
        }
    }

    func post() {

        let date = dateLabel.text
        let time = timeLabel.text
        let latitude = latitudeLabel.text
        let longitude = longitudeLabel.text
        let sightingDescription = descriptionLabel.text

        let post: [String : AnyObject] = ["Date" : date as AnyObject,
                                          "Time" : time as AnyObject,
                                          "Latitude" : latitude as AnyObject,
                                          "Longitude" : longitude as AnyObject,
                                          "Description" : sightingDescription as AnyObject]

        var ref: DatabaseReference!
        ref = Database.database().reference()
        ref.child("Sightings").childByAutoId().setValue(post)

    }

    @IBAction func saveButton(_ sender: Any) {

        post()

        // Create the alert controller
        let alertController = UIAlertController(title: "Sighting Logged Successfully", message: "Your logged entry will now show up on the map for others to see. Thank You!", preferredStyle: .alert)

        // Create the actions
        let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default) {
            UIAlertAction in
            NSLog("OK Pressed")

        }

        // Add the actions
        alertController.addAction(okAction)

        // Present the controller
        self.present(alertController, animated: true, completion: nil)

    }

}

推荐答案

在完成此工作之后，我最终通过使用以下函数并在viewDidLoad()中调用了它来使其工作

After working on this I've eventually got it to work by using the following function and calling it in viewDidLoad()

func displayAnnotations() {

        let ref = Database.database().reference()
        ref.child("Sightings").observe(.childAdded, with: { (snapshot) in

            let date = (snapshot.value as AnyObject!)!["Date"] as! String!
            let time = (snapshot.value as AnyObject!)!["Time"] as! String!
            let latitude = (snapshot.value as AnyObject!)!["Latitude"] as! String!
            let longitude = (snapshot.value as AnyObject!)!["Longitude"] as! String!
            let desc = (snapshot.value as AnyObject!)!["Description"] as! String!

            let annotation = MKPointAnnotation()

            annotation.coordinate = CLLocationCoordinate2D(latitude: (Double(latitude!))!, longitude: (Double(longitude!))!)
            annotation.title = date
            annotation.subtitle = time
            self.map.addAnnotation(annotation)

        })}

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