Getting an error when my app tries to download JSON

Question

I finally started updating the BonusData.json file that my app uses. Now I am getting an error when it tries to load the data. The complete code is below but I am getting "JSON Download Failed", which is contained in the downloadJSON function.

If I'm reading my code right, that would mean that I'm encountering an error in the

let posts = try JSONDecoder().decode(JsonFile.self, from: data)
completed(posts.bonuses)

section, but I'm not sure how to troubleshoot that any further. What is supposed to be happening is that the app looks at the server, downloads the JSON and then saves it locally to be used to populate the UITableView. If there is no data connection, then it should not care, and just use the local saved version. Because the app is loading up blank, I'm assuming it is also not working as it is intended.

Here is the complete code:

import UIKit
import os.log
import Foundation

class BonusListViewController: UITableViewController {
    var bonuses = [JsonFile.JsonBonuses]()
    var filteredBonuses = [JsonFile.JsonBonuses]()
    var detailViewController: BonusDetailViewController? = nil

    let defaults = UserDefaults.standard

    let searchController = UISearchController(searchResultsController: nil)

    override func viewDidLoad() {
        super.viewDidLoad()

        // MARK: Search Support
        searchController.searchResultsUpdater = self
        searchController.obscuresBackgroundDuringPresentation = false
        searchController.searchBar.placeholder = "Enter two letter state to filter"
        navigationItem.searchController = searchController
        definesPresentationContext = true

        // MARK: Settings Data Struct
        struct Constants {
            struct RiderData {
                let riderNumToH = "riderNumToH"
                let pillionNumToH = "pillionNumToH"
            }
            struct RallyData {
                let emailDestinationToH = "emailDestinationToH"
            }
        }
        //MARK: Load the bonuses
        print("About to call loadBonuses")
        loadBonuses { [weak self] bonuses in
            self?.bonuses = bonuses ?? []
            DispatchQueue.main.async {
                self?.tableView.reloadData()
            }
            print("loadBonuses called")
        }
    }

    // MARK: - Table View Configuration
    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if isFiltering() {
            print("Showing \(filteredBonuses.count) Filtered Results")
            return filteredBonuses.count
        }

        print("Found \(bonuses.count) rows in section.")
        return bonuses.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cellIdentifier = "BonusListViewCell"
        guard let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as? BonusListViewCell else {
            fatalError("The dequeued cell is not an instance of BonusListViewCell.")
        }
        // let bonus = bonuses[indexPath.row]
        let bonus: JsonFile.JsonBonuses
        if isFiltering() {
            bonus = filteredBonuses[indexPath.row]
        } else {
            bonus = bonuses[indexPath.row]
        }

        let urlString = "http://tourofhonor.com/appimages/"+(bonus.imageName)
        let url = URL(string: urlString)
        cell.primaryImage.downloadedFrom(url: url!)
        cell.nameLabel.text = bonus.name.capitalized
        cell.bonusCodeLabel.text = bonus.bonusCode.localizedUppercase
        cell.categoryLabel.text = bonus.category
        cell.valueLabel.text = "\(bonus.value)"
        cell.cityLabel.text = "\(bonus.city.capitalized),"
        cell.stateLabel.text = bonus.state.localizedUppercase

        return cell
    }

    // MARK: Functions
    // MARK: - Fetch JSON from ToH webserver

    func downloadJSON(completed: @escaping ([JsonFile.JsonBonuses]?) -> ()) {
        let url = URL(string: "http://tourofhonor.com/BonusData.json")!
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            if error == nil, let data = data {
                do {
                    let posts = try JSONDecoder().decode(JsonFile.self, from: data)
                    completed(posts.bonuses)
                    print("URLSession did not fail")
                } catch {
                    print("JSON Download Failed")
                }
            } else {
                print("downloadJSON completed")
                completed(nil)
            }
        }.resume()
    }

    func saveBonuses(_ bonuses: [JsonFile.JsonBonuses], to url: URL) {
        try? FileManager.default.removeItem(at: url)
        do {
            let data = try JSONEncoder().encode(bonuses)
            try data.write(to: url)
            print("saveBonuses successful")
        } catch {
            print("Error saving bonuses to file:", error)
        }
    }

    func loadBonusesFromFile(_ url: URL) -> [JsonFile.JsonBonuses]? {
        do {
            let data = try Data(contentsOf: url)
            let bonuses = try JSONDecoder().decode([JsonFile.JsonBonuses].self, from: data)
            print("loadBonusesFromFile successful")
            return bonuses
        } catch {
            print("Error loading bonuses from file:", error)
            return nil
        }
    }

    func loadBonuses(completion: @escaping ([JsonFile.JsonBonuses]?) -> Void) {
        let localBonusesURL = try! FileManager.default
            .url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
            .appendingPathComponent("BonusData.json")
        downloadJSON { bonuses in
            if let bonuses = bonuses {
                completion(bonuses)
                self.saveBonuses(bonuses, to: localBonusesURL)
            } else {
                print("versions did not match")
                completion(self.loadBonusesFromFile(localBonusesURL))
            }
        }
    }

    func searchBarIsEmpty() -> Bool {
        // Returns true if the text is empty or nil
        return searchController.searchBar.text?.isEmpty ?? true
    }

    func filterContentForSearchText(_ searchText: String, scope: String = "All") {
        filteredBonuses = bonuses.filter({( bonus: JsonFile.JsonBonuses) -> Bool in
            return bonus.state.localizedCaseInsensitiveContains(searchText)
        })
        tableView.reloadData()
    }

    func isFiltering() -> Bool {
        return searchController.isActive && !searchBarIsEmpty()
    }

    // MARK: - Navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let destination = segue.destination as? BonusDetailViewController {
            destination.bonus = bonuses[(tableView.indexPathForSelectedRow?.row)!]
        }
    }
}

extension BonusListViewController: UISearchResultsUpdating {
    // MARK: - UISearchResultsUpdating Delegate
    func updateSearchResults(for searchController: UISearchController) {
        filterContentForSearchText(searchController.searchBar.text!)
    }
}

The JSON is hosted here: http://tourofhonor.com/BonusData.json

Answer 1

It looks like the JSON you're trying to download is not formatted correctly. It's missing a comma between objects, and it has an extra comma at the end of the list.

There are a number of tools to validate JSON, but one accessible one is https://jsonlint.com/. If you paste the output from http://tourofhonor.com/BonusData.json there, it will highlight the formatting errors for you and give you some guidance on how to fix them.