Fetching JSON data from an API in Swift

Question

I recently started using learning to code in Swift and I have been struggling to fetch data from an API. This is what the data looks like:

{
   "status":200,
   "posts":[
      {
         "text":"djnkdnwnjdewkn",
         "date":"08/07/2012"
      },
      {
         "text":"dskndkc ksdskj n",
         "date":"08/17/2012"
      },
      {
         "text":"dkjdjincidjn",
         "date":"09/07/2012"
      }
   ]
}

And here is the code I have used:

import SwiftUI
import Foundation
import Combine

struct Post: Codable {
    public var text, date: String
}

struct Feed: Codable {
    public var status: Int
    public var posts: [Post]
}


class FetchPosts: ObservableObject {
    @Published var post = [Post]()

    init() {
        let url = URL(string: "api goes here")!
        URLSession.shared.dataTask(with: url) {(data, response, error) in
            do {
                if let postData = data {
                    let decodedData = try JSONDecoder().decode([Post].self, from: postData)
                    DispatchQueue.main.async {
                        self.post = decodedData
                    }
                } else {
                    print("No data")
                }
            } catch {
                print("Error")
            }
        }.resume()
    }
}

struct FeedView: View {
    @ObservedObject var fetch = FetchPosts()
    var body: some View {
        ScrollView{
            VStack {
                ForEach(fetch.posts) { post in
                    VStack(alignment: .leading) {
                        Text(post.text)
                        Text("\(post.date)")
                            .font(.system(size: 13))
                  
                    }
                }
            }
        }
    }
}

I haven't been able to generate any output so far. I'm not sure if the problem is with the way I created the structs or if I'm just not using the JSONDecoder correctly. Any pointers would be greatly appreciated!

print("Error") => print("Error: \(error)") that might be the first step you are missing. — Larme
– Larme, Commented Apr 14, 2021 at 7:36
See this question and answer. This goes into great detail about how to fetch and convert JSON into data you can use. — Yrb
– Yrb, Commented Apr 14, 2021 at 13:52

Joakim Danielson · Accepted Answer · 2021-04-14 06:31:35Z

0

You have correctly created a struct Feed but you are not using it. Call decode on it instead of [Post],

let decodedData = try JSONDecoder().decode(Feed.self, from: postData)

Also never print a hard coded string when handling errors so replace print("Error") with print(error)

Your code then becomes

do {
    if let postData = data {
        let decodedData = try JSONDecoder().decode(Feed.self, from: postData)
        DispatchQueue.main.async {
            self.post = decodedData.posts
        }
    } else {
         print("No data")
    }
} catch {
    print(error)
}

answered Apr 14, 2021 at 6:31

Joakim Danielson

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1 Comment

Joakim Danielson Over a year ago

@Safade, any feedback on this?

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