Swift 4 get song for every channel - json

Question

I got the same error when I try to get previous and song that play right now for every channel. I think something is wrong in my struct Root and playlist because data is not in the correct format.I am using Swift 4 and trying to learn JSON, but its hard. Previous struct is same as Song struct. How do I fix my error?
My code looks now:
import UIKit
struct Root : Decodable {
let copyright : String
let channels : [Channel]
let pagination : Pagination
}
struct Channel : Decodable {
let image : String
let imagetemplate : String
let color : String
let tagline : String?
let siteurl : String
let id : Int
let url : URL?
let statkey : String?
let scheduleurl : String
let channeltype : String
let name : String
}
struct Pagination : Decodable {
let page, size, totalhits, totalpages : Int
let nextpage : URL
}
struct Playlist : Decodable{
let id : Int
let name :String
let prev : [previoussong]
let song : [Song]
}
struct previoussong : Decodable {
let title : String
let description : String
let artist : String
let composer :String
let conductor : String
let albumname : String
let recordlabel : String
let lyricist : String
let producer : String
let starttimeutc : String
let stopttimeutc : String
}
struct Song : Decodable {
let title : String
let description : String
let artist : String
let composer :String
let conductor : String
let albumname : String
let recordlabel : String
let lyricist : String
let producer : String
let starttimeutc : String
let stopttimeutc : String
}
import UIKit
class ViewController: UIViewController,UITableViewDataSource {
var auth = SPTAuth.defaultInstance()!
var session:SPTSession!
var loginUrl: URL?
var tests = [Channel]()
//var pl = [Playlist]()
var stationsName:String?
#IBOutlet weak var tableV: UITableView!
#IBOutlet weak var image: UIImageView!
#IBOutlet weak var statLabel: UILabel!
#IBOutlet weak var songLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
tableV.dataSource = self
downloadStations()
}
func downloadStations(){
let test2 = "http://api.sr.se/api/v2/channels?format=json"
let play = "http://api.sr.se/api/v2/playlists/rightnow?format=json"
let url = URL(string: test2)
URLSession.shared.dataTask(with: url!){ (data , response, error) in
do{
let root = try JSONDecoder().decode(Root.self, from: data!)
self.tests = root.channels
for eachStations in self.tests {
self.stationsName = eachStations.name
print(" " + self.stationsName!)
DispatchQueue.main.async {
self.tableV.reloadData()
}
}
}
catch{
print(error.localizedDescription)
}
}.resume()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return tests.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style : .default, reuseIdentifier : nil)
cell.textLabel?.text = tests[indexPath.row].name
return cell
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

The data you're getting from api.sr.se/api/v2/playlists/rightnow?format=json does not always have the correct structure. Notice that sometimes you will get json that starts with a copyright field, while other times you get something like this:
{
"playlist": {
"previoussong": {
"title": "Stir Fry",
"description": "Migos - Stir Fry",
"artist": "Migos",
"composer": "Quavious Marshall/Pharrell Williams",
"recordlabel": "Universal",
"starttimeutc": "\/Date(1521137326000)\/",
"stoptimeutc": "\/Date(1521137510000)\/"
},
...
When you attempt to decode into Root, the decoder looks in the json for something that looks like your Root class, something like this:
{
"copyright": "Copyright Sveriges Radio 2018. All rights reserved.",
"channels": [{
"id": 4540,
"name": "Ekot",
"playlists": {
"playlist": {
"channel": {
"id": 4540,
"name": "Ekot sänder direkt"
}
If it can't find something like that in the json, it says the data is missing. You will have to figure out a way to tell when to decode into Root, and when the data isn't appropriate for Root.