Update: Chris discusses this in-depth here: CodeWithChris
Greetings!
After completing the Lesson app with the networking component, while running the app this warning displays on Xcode 13 iOS 15:
Full warning message:
LearningApp[14356:673748] [SwiftUI] Publishing changes from background threads is not allowed; make sure to publish values from the main thread (via operators like receive(on:)) on model updates.
I heard that the latest Swift/ Xcode now supports asnyc/ await threads. Does this warning relate to that? Should we be concerned with it?
Perhaps, it doesn’t matter, because that thread will not publish anymore changes. I’m not sure…
Here’s a link to my code base.
While here is my method, which fetches the JSON from a remote server. Note that this code gets called after the method, which parses the JSON locally in the init method:
func getRemoteData() {
// String path for content
let urlString = "https://raw.githubusercontent.com/agholson/Learning-App/master/LessonConfigData/module2.json"
// Create a URL object that returns an optional URL
let url = URL(string: urlString)
// Check that the URL exists
guard url != nil else {
// Could not create the URL
return
}
// Create a URLRequest object - where we force unwrap our URL object, because we already checked it exists
let request = URLRequest(url: url!)
// Create a session based on the single session object for each app
let session = URLSession.shared
// Raw data fetched in data, response contains more details, while error contains any errors
let dataTask = session.dataTask(with: request) { data, response, error in
// Check if it hit any errors
guard error == nil else {
return
}
// Handle the response
// Create a JSON decoder
do {
let decoder = JSONDecoder()
// Decode - can safely force unrwapp, because checked for errors above
let modules = try decoder.decode([Module].self, from: data!)
// Append parsed modules into modules property
self.modules += modules
}
catch {
// Could not parse the JSON
}
}
// Issue GET request, then parses it in the handler above
dataTask.resume()
}
How did you know this would be the solution?