Allow JSON fragments with Decodable - json

Question

import UIKit
class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource {
//#IBOutlet weak var ingredientText: UILabel!
struct Recipes: Decodable {
let recipe_id:String?
let image_url:String?
let source_url:String?
let f2f_url:String?
let title:String?
let publisher:String?
let social_rank:Float64?
let page:Int?
let ingredients:[String]?
private enum CodingKeys: String, CodingKey{
case recipe_id = "recipe_id"
case image_url = "image_url"
case source_url = "source_url"
case f2f_url = "f2f_url"
case title = "title"
case publisher = "publisher"
case social_rank = "social_rank"
case page = "page"
case ingredients = "ingredients"
}
}
var recipes = [Recipes]()
var food = "chicken"
var food2 = "peas"
var food3 = "onions"
//var recipeData = [Recipe]
#IBOutlet weak var tableView: UITableView!
fileprivate func getRecipes() {
let jsonURL = "http://food2fork.com/api/search?key=264045e3ff7b84ee346eb20e1642d9d9264045e3ff7b84ee346eb20e1642d9d9&food=chicken&food2=onions&food3=peas"
guard let url = URL(string: jsonURL) else{return}
URLSession.shared.dataTask(with: url) {(data, _ , err) in
DispatchQueue.main.async {
if let err = err{
print("failed to get data from URL",err)
return
}
guard let data = data else{return}
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
self.recipes = try decoder.decode([Recipes].self, from: data)
self.tableView.reloadData()
}catch let jsonERR {
print("Failed to decode",jsonERR)
}
}
}.resume()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return recipes.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: .subtitle, reuseIdentifier: "cell")
let recipe = recipes[indexPath.row]
cell.textLabel?.text = recipe.title
return cell
}
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.navigationBar.prefersLargeTitles = true
navigationItem.title = "Ingredients"
getRecipes()
}
}
I am getting the error:
JSON text did not start with array or object and option to allow fragments not set." UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.})))

Answer 1

JSONDecoder doesn't provide any JSONSerialization.ReadingOptions.
You could make a manual check whether the first byte of the data is an opening square bracket <5b> or brace <7b>
guard let data = data, let firstByte = data.first else { return }
guard firstByte == 0x5b || firstByte == 0x7b else {
let string = String(data: data, encoding: .utf8)!
print(string)
return
}
However I'd recommend to use the response parameter to check for status code 200
URLSession.shared.dataTask(with: url) { (data, response , error) in
if let response = response as? HTTPURLResponse, response.statusCode != 200 {
print(response.statusCode)
return
}
...
Note: If the CodingKeys match exactly the struct members you can omit the CodingKeys and as you are explicitly using .convertFromSnakeCase you are encouraged to name the struct members recipeId, imageUrl, sourceUrl etc.

Answer 2

You want to decode [Recipe], that is, an Array of Recipe. That mean the first (non-whitespace) character in data has to be [ (to make it a JSON array), and it's not. So you need to figure out why you're getting the wrong response, and fix that problem. Try converting data to a String and printing it:
print(String(data: data, encoding: .utf8))