How could you access the GitHub API in Swift? - swift

Question

I'd like to make an update detection system in my macOS SwiftUI app by pulling the latest release from GitHub via the API and then comparing the tag. How would I go about accessing the API from Swift? I've tried using the methods from here, medium.com, here, swifttom.com and here, steveclarkapps.com but none of them accomplish what I'm trying to do.
For the first method, the code functions with the provided example API, but doesn't work with the GitHub API and it returns this error instead:
Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.typeMismatch(Swift.Array<Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Array<Any> but found a dictionary instead.", underlyingError: nil))
Method 2 suffers the same issue.
I couldn't even get enough of method 3's code working to try it.
Here's my adapted code based off of the medium.com method:
Model.swift
import Foundation
struct TaskEntry: Codable {
let id: Int
let tag_name: String
let name: String
}
ContentView.swift
import SwiftUI
struct ContentView: View {
#State var results = [TaskEntry]()
var body: some View {
List(results, id: \.id) { item in
VStack(alignment: .leading) {
Text(item.name)
}
}.onAppear(perform: loadData)
}
func loadData() {
guard let url = URL(string: "https://api.github.com/repos/NCX-Programming/RNGTool/releases/latest") 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 response = try! JSONDecoder().decode([TaskEntry].self, from: data) /*{*/
DispatchQueue.main.async {
self.results = response
}
return
/*}*/
}
}.resume()
}
}
Commented out code and variable names that seem irrelevant are just leftovers.
OS: macOS Big Sur 11.6
Xcode version: 13.0

Answer 1

Open this in your browser:
https://api.github.com/repos/NCX-Programming/RNGTool/releases/latest
You will notice it is not an array but an object. You should be decoding an object like this:
JSONDecoder().decode(TaskEntry.self, from: data)
Edit:
This requires you to change your view. Notice this is no longer a List because you are no longer fetching an array but a single item:
struct TaskEntry: Codable {
let id: Int
let tagName: String
let name: String
}
struct ContentView: View {
#State var entry: TaskEntry? = nil
var body: some View {
VStack(alignment: .leading) {
if let entry = entry {
Text("\(entry.id)")
Text(entry.name)
Text(entry.tagName)
} else {
ProgressView()
}
}
.onAppear(perform: loadData)
}
func loadData() {
guard let url = URL(string: "https://api.github.com/repos/NCX-Programming/RNGTool/releases/latest") else {
print("Invalid URL")
return
}
let request = URLRequest(url: url)
URLSession.shared.dataTask(with: request) { data, response, error in
if let error = error {
// TODO: Handle data task error
return
}
guard let data = data else {
// TODO: Handle this
return
}
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
do {
let response = try decoder.decode(TaskEntry.self, from: data)
DispatchQueue.main.async {
self.entry = response
}
} catch {
// TODO: Handle decoding error
print(error)
}
}.resume()
}
}
NOTICE: I did some other improvements as well
Use JSONDecoder to convert from snake case to camel case
Added do catch block so your app doesn't crash
Check for errors before decoding
Added loading indicator (had to put something in the else)
However,
As our discussion you are probably calling the wrong endpoint. That endpoint is not returning an array but a single object, you can tell this because the JSON response begins with { rather than [
I've adjusted my answer to change the endpoint I believe you should be calling:
struct TaskEntry: Codable {
let id: Int
let tagName: String
let name: String
}
struct ContentView: View {
#State var results: [TaskEntry]? = nil
var body: some View {
if let results = results {
List(results, id: \.id) { item in
VStack(alignment: .leading) {
Text(item.name)
}
}
} else {
VStack(alignment: .leading) {
ProgressView()
.onAppear(perform: loadData)
}
}
}
func loadData() {
guard let url = URL(string: "https://api.github.com/repos/NCX-Programming/RNGTool/releases") else {
print("Invalid URL")
return
}
let request = URLRequest(url: url)
URLSession.shared.dataTask(with: request) { data, response, error in
if let error = error {
// TODO: Handle data task error
return
}
guard let data = data else {
// TODO: Handle this
return
}
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
do {
let response = try decoder.decode([TaskEntry].self, from: data)
DispatchQueue.main.async {
self.results = response
}
} catch {
// TODO: Handle decoding error
print(error)
}
}.resume()
}
}