Why is my JSON code in Swift not parsing? - json

Question

Disclaimer: Very basic question below. I am trying to learn the basics of IOS development.
I'm currently trying to parse data from an API to a SwiftUI project and am not able to successfully do so.
The code goes as follows:
import SwiftUI
struct Poem: Codable {
let title, author: String
let lines: [String]
let linecount: String
}
class FetchPoem: ObservableObject {
// 1.
#Published var poems = [Poem]()
init() {
let url = URL(string: "https://poetrydb.org/random/1")!
// 2.
URLSession.shared.dataTask(with: url) {(data, response, error) in
do {
if let poemData = data {
// 3.
let decodedData = try JSONDecoder().decode([Poem].self, from: poemData)
DispatchQueue.main.async {
self.poems = decodedData
}
} else {
print("No data")
}
} catch {
print("Error")
}
}.resume()
}
}
struct ContentView: View {
#ObservedObject var fetch = FetchPoem()
let joined = fetch.poem.lines.joined(separator: "\n")
var body: some View {
Text(fetch.poem.title)
.padding()
Text( \(joined) )
.padding()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
The build currently fails. It's throwing me the following errors:
Initializer 'init(_:)' requires that 'Binding<Subject>' conform to 'StringProtocol'
Referencing subscript 'subscript(dynamicMember:)' requires wrapper 'ObservedObject<FetchPoem>.Wrapper'
Value of type 'FetchPoem' has no dynamic member 'poem' using key path from root type 'FetchPoem'
Moreover, I am attempting to append the array "Lines" into one main String variable "Joined". However, I am not sure this works... The error is "String interpolation can only appear inside a string literal". Would love some help if anyone knows...
Any ideas? All help is appreciated.
** Edited Code - Q2
import SwiftUI
struct Poem: Codable, Hashable {
let title, author: String
let lines: [String]
let linecount: String
}
class FetchPoem: ObservableObject {
#Published var poems = [Poem]()
func getPoem() {
let url = URL(string: "https://poetrydb.org/random/1")!
// 2.
URLSession.shared.dataTask(with: url) {(data, response, error) in
do {
if let poemData = data {
// 3.
let decodedData = try JSONDecoder().decode([Poem].self, from: poemData)
DispatchQueue.main.async {
self.poems = decodedData
}
} else {
print("No data")
}
} catch {
print("Error")
}
}.resume()
}
}
struct ContentView: View {
#ObservedObject var fetch = FetchPoem()
var body: some View {
VStack {
if let poem = fetch.poems.first {
Button("Refresh") {getPoem}
Text("\(poem.author): \(poem.title)").bold()
Divider()
ScrollView {
VStack {
ForEach(poem.lines, id: \.self) {
Text($0)
}
}
}
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}

Answer 1

Most probably you wanted this (because poems is an array) - tested with Xcode 12.1 / iOS 14.1
struct Poem: Codable, Hashable {
let title, author: String
let lines: [String]
let linecount: String
}
// ...
struct ContentView: View {
#ObservedObject var fetch = FetchPoem()
var body: some View {
List {
ForEach(fetch.poems, id: \.self) {
Text("\($0.author): \($0.title)")
}
}
}
}
... , and next might be wrapping that into NavigationView/NavigationLink with shown each poem in desination view.
Of showing lines as follows:
var body: some View {
VStack {
if let poem = fetch.poems.first {
Text("\(poem.author): \(poem.title)").bold()
Divider()
ScrollView {
VStack {
ForEach(poem.lines, id: \.self) {
Text($0)
}
}
}
}
}
}