Populating tableview from structs instead of arrays - ios

Question

I'm making a small project to practice serializing JSON in Swift 4 using structs... it gets top stories from the New York Times API and puts them into a table view. Currently I'm getting the data I need from the JSON and filling some arrays with the stuff I need (headlines, abstracts, etc).
Someone advised me to skip that step and instead populate the table view directly from the structs.
struct TopStoriesResponse: Decodable {
let status: String
let results: [Story]
}
struct Story: Decodable {
let title: String
let abstract: String
let url: String
let multimedia: [Multimedia]
private enum CodingKeys: String, CodingKey {
case title
case abstract
case url
case multimedia
}
init(from decoder:Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
title = try container.decode(String.self, forKey: .title)
abstract = try container.decode(String.self, forKey: .abstract)
url = try container.decode(String.self, forKey: .url)
multimedia = (try? container.decode([Multimedia].self, forKey: .multimedia)) ?? []
}
}
struct Multimedia: Decodable {
let url: String
let type: String
}
var storyData = [Story]()
And in my cellForRowAt method:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "storyCell", for: indexPath) as! StoryTableViewCell
let stories = storyData[indexPath.row]
print("Titles: \(stories.title)")
cell.headlineLabel.text = stories.title
cell.abstractLabel.text = stories.abstract
return cell
}
When I run the app, the table view is empty and my print statement confirmed that stories.title is empty (everything showed up before when I was using arrays).
This is the function that grabs the data if it's applicable here, i'll scrap all the code that passes the data into arrays if I can use the structs instead:
func getJSON(completionHandler: #escaping (Bool) -> ()) {
let jsonUrlString = "https://api.nytimes.com/svc/topstories/v1/business.json?api-key=f4bf2ee721031a344b84b0449cfdb589:1:73741808"
guard let url = URL(string: jsonUrlString) else {return}
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data, err == nil else {
print(err!)
return
}
do {
let response = try
JSONDecoder().decode(TopStoriesResponse.self, from: data)
// Pass results into arrays (title, abstract, url, image)
for result in response.results {
let headlines = result.title
let abstracts = result.abstract
let url = result.url
self.headlines.append(headlines)
self.abstracts.append(abstracts)
self.urls.append(url)
for imageResults in result.multimedia {
let images = imageResults.url
self.images.append(images)
}
}
completionHandler(true)
} catch let jsonErr {
print("Error serializing JSON", jsonErr)
}
}.resume()
}
Do I need to pass the data back into the structs the way I was doing it with the arrays? I was under the impression that let response = try JSONDecoder().decode(TopStoriesResponse.self, from: data) did that already.

Answer 1

You need
let response = try JSONDecoder().decode(TopStoriesResponse.self, from: data)
self.storyData = response.results
DispatchQueue.main.async {
self.tableView.reloadData()
}
the other arrays content is irrelevant here as you don't use them as the dataSource of the table

Answer 2

There seems to be a mismatch in your data models. On the one hand, your JSON data is being put into four arrays: self.headlines, self.abstracts, self.urls, and self.images. But your table view knows nothing about any of that; it depends entirely on a different array, storyData. You need to bring those two data models together, if you see what I mean. Download the data, rejigger it into storyData, and then tell the table view to reloadData.