SwiftUI List and URLSession + JSONDecode - json

Question

hi everyone I'm newbie in Swift
I ask for help why the data is not displayed in List? Please help me a fix it.
I make a Model Data, and take a data from URl and parse it
My model:
struct ResponseData: Codable{
var userId: String
var id: String
var title: String
var body: String
}
My code in Content view:
import SwiftUI
struct ContentView: View {
#State var responseData = [ResponseData]()
var body: some View {
List(responseData, id: \.id ) { item in
Text("\(item.body)")
}
.task {
await loadData()
}
}
func loadData () async {
let urlString = "https://jsonplaceholder.typicode.com/posts"
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else {return}
guard error == nil else {return}
do {
let postData = try JSONDecoder().decode(ResponseData.self, from: data)
} catch let error {
print(error)
}
}.resume()
}
}

Answer 1

There are many issues in the code.
The most significant ones are
In the struct userId and id are Int.
The JSON root object is an array, please note the starting [.
You don't update the model after receiving the data.
As you are using async/await anyway take full advantage of the pattern.
The JSON API returns posts, so how about to name the struct Post?
struct Post: Codable, Identifiable {
let userId: Int
let id: Int
let title: String
let body: String
}
struct ContentView : View {
#State var posts = [Post]()
var body : some View {
List(posts) { post in
Text(post.body)
}
.task {
do {
posts = try await loadData()
} catch {
print(error)
}
}
}
func loadData() async throws -> [Post] {
let urlString = "https://jsonplaceholder.typicode.com/posts"
let url = URL(string: urlString)!
let (data, _) = try await URLSession.shared.data(for: URLRequest(url: url))
return try JSONDecoder().decode([Post].self, from: data)
}
}