Parsing JSON - "Variable 'jsonObject' used before being initialized

Question

I am having a problem with a JSON library I am using for an iOS 9.0 project, on Xcode 7 beta 5, running on OS X El Cap.

I followed this link to make a part of my app that involved some basic MapKit functionality. In this "part", I have to parse JSON data into "issue locations" (it's an app for a school newspaper, and we're going to have a map of all locations where they drop off issues).

Here is my problem (I don't understand it, as I am a beginner iOS developer). I get an error on the following line, that says "Variable 'jsonObject' used before being initialized".

The line in question is the third "paragraph" in the "loadInitialData" function.

if let jsonObject = jsonObject as? [String: AnyObject],

And here is all of my code for the "MapViewController.swift" file governing everything that happens in my MapKit view.

import UIKit
import MapKit
import CoreLocation

class MapViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {

// Map View outlet declaration
@IBOutlet weak var mapView: MKMapView!

// Hamburger button declaration
@IBOutlet weak var menuButton:UIBarButtonItem!

var locationManager: CLLocationManager?

// Creating a variable to hold the "IssueLocation" objects from the JSON file
var issueLocations = [IssueLocation]()

override func viewDidLoad() {
    super.viewDidLoad()

    // Hamburger button configuration
if self.revealViewController() != nil {
    menuButton.target = self.revealViewController()
    menuButton.action = "revealToggle:"
    self.view.addGestureRecognizer(self.revealViewController().panGestureRecognizer())
    }

    // Setting the Map type to standard
    mapView.mapType = MKMapType.Standard

    // Configuring locationManager and mapView delegate
    locationManager = CLLocationManager()
    mapView.delegate = self

    // Set the center of campus as the first location, before we show the actual user location
    let initialLocation = CLLocation(latitude: 44.226397, longitude: -76.495571)
    let regionRadius: CLLocationDistance = 1000

    // Centering map on center of campus
    func centerMapOnLocation(location: CLLocation) {
        let coordinateRegion = MKCoordinateRegionMakeWithDistance(location.coordinate, regionRadius * 2.0, regionRadius * 2.0)
        mapView.setRegion(coordinateRegion, animated: true)
    }

    loadInitialData()
    mapView.addAnnotations(issueLocations)

    // Show user location and start updating user location
    mapView.showsUserLocation = true
    locationManager?.startUpdatingLocation()

//        // Show a sample issue location on the Map
//        let IssueLocation = IssueLocation(locationName: "Stirling Hall, West  Entrance", coordinate: CLLocationCoordinate2D(latitude: 44.22468034747186, longitude: -76.49805217981339))
//        
//        mapView.addAnnotation(IssueLocation)

    // Do any additional setup after loading the view.
}

func mapView(mapView: MKMapView, didUpdateUserLocation userLocation: MKUserLocation) {
    mapView.centerCoordinate = userLocation.location!.coordinate
}

func loadInitialData() {

    let fileName = NSBundle.mainBundle().pathForResource("IssueLocations", ofType: "json");
    var readError : NSError?
    var data: NSData?

    do {
        data = try NSData(contentsOfFile: fileName!, options: NSDataReadingOptions(rawValue: 0))
    } catch _ {
        data = nil
    }

    var error: NSError?
    let jsonObject: AnyObject!
    if let data = data {

        do {
            jsonObject = try NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions(rawValue: 0))
        } catch _ {
            jsonObject = nil
        }

    }

    if let jsonObject = jsonObject as? [String: AnyObject],
        let jsonData = JSONValue.fromObject(jsonObject)?["data"]?.array {
            for issueLocationJSON in jsonData {
                let issueLocation = IssueLocation.fromJSON(issueLocationJSON.array!)
                        issueLocations.append(issueLocation)



            }

    }
}

// Checking location authorization status and requesting permission from user if status is not ".AuthorizedWhenInUse"
func checkLocationAuthorizationStatus() {

    if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
        mapView.showsUserLocation = true
     } else {
        locationManager?.requestWhenInUseAuthorization()
        }
    }

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    checkLocationAuthorizationStatus()
    }

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/


}

Answer 1

If if let data = data evaluates to false, then jsonObject will not be initialized since all the initialization for that object happens inside that if statement. Try initializing jsonObject to nil when you create the variable.