Fetching and decoding unkwown error in Swift [closed] - swift

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I'm trying to fetch the data and decode it into structs, and then display that data in a list.
I used quicktype.io to parse JSON to Swift. This part seems to be okay.
struct Response: Codable {
var results: [User]
}
struct User: Codable {
let id: String
let isActive: Bool
let name: String
let age: Int
let company, email, address, about: String
let registered: Date
let tags: [String]
let friends: [Friend]
}
struct Friend: Codable {
let id, name: String
}
This is the rest of the code, where I try to decode the data(where the error occurs). Here is a link to the JSON.
struct ContentView: View {
#State private var users = [User]()
var body: some View {
List {
ForEach(users, id: \.id) { user in
Text(user.name)
}
}.onAppear(perform: loadData)
}
func loadData() {
guard let url = URL(string: "https://www.hackingwithswift.com/samples/friendface.json") else {
print("Invalid URL")
return
}
let request = URLRequest(url: url)
URLSession.shared.dataTask(with: request) { data, response, error in
if let data = data {
if let decodedResponse = try? JSONDecoder().decode(Response.self, from: data) {
// we have good data – go back to the main thread
DispatchQueue.main.async {
// update our UI
print(decodedResponse.results)
users = decodedResponse.results
}
// everything is good, so we can exit
return
}
}
// if we're still here it means there was a problem
print("Fetch failed: \(error?.localizedDescription ?? "Unknown error")")
}.resume()
}
}

Answer 1

You have to decode on type [User] not Response. Look at the response and you'll see that the top-level JSON is an Array, not a Dictionary. Also, update your code to get meaningful error messages. Use do try catch syntax instead of if let try?.
func loadData() {
guard let url = URL(string: "https://www.hackingwithswift.com/samples/friendface.json") else {
print("Invalid URL")
return
}
let request = URLRequest(url: url)
URLSession.shared.dataTask(with: request) { data, response, error in
if let data = data {
do {
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
let users = try decoder.decode([User].self, from: data)
DispatchQueue.main.async {
print(users)
self.users = users
}
} catch {
print(error)
}
} else {
// if we're still here it means there was a problem
print("Fetch failed: \(error?.localizedDescription ?? "Unknown error")")
}
}.resume()
}
Update: Also, need to add dateDecodingStrategy to make the decoding work correctly.