在 UILabel (Swift 4) 中显示来自解码 JSON 的信息

Question

我正在尝试显示从 JSON 中获取的信息。我已经使用 .decode 来获取它。现在我想把它的文本放到我故事板上的一个简单标签上。在“.resume()”下的底部是我的尝试，但它不起作用。我似乎无法弄清楚这一点。

---

import UIKit


struct WebsiteDescription: Decodable {
    var name : String
    var description : String
    var courses : [Course]

}


struct Course: Decodable {
    let id: Int
    let name: String
    let link: String
    let imageUrl: String
}

class ViewController: UIViewController {

    @IBOutlet weak var displayLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        let jsonUrlString = "https://api.letsbuildthatapp.com/jsondecodable/website_description"
        guard let url = URL(string: jsonUrlString) else {return}
        URLSession.shared.dataTask(with: url) { (data, response, err) in
            guard let data = data else {return}

            do {
                let websiteDescription = try JSONDecoder().decode(WebsiteDescription.self, from: data)
                print(websiteDescription.name, websiteDescription.description, websiteDescription.courses)
                //let courses = try JSONDecoder().decode([Course].self, from: data)
            } catch let jsonErr {
                print("Error serializing json", jsonErr)
            }

        }.resume()

        let displayLabel.text = websiteDescription.name

    }

}

Answer 1

您需要在 do 方法中更新您的标签。此外，您应该从主线程执行此操作，以便可以更新 UI。我已经更新了下面的代码。

import UIKit

struct WebsiteDescription: Decodable { 
    var name : String 
    var description : String 
    var courses : [Course]
}

struct Course: Decodable { 
    let id: Int 
    let name: String 
    let link: String 
    let imageUrl: String 
}

class ViewController: UIViewController {

    @IBOutlet weak var displayLabel: UILabel!

    override func viewDidLoad() {
    super.viewDidLoad()

        let jsonUrlString = "https://api.letsbuildthatapp.com/jsondecodable/website_description"
        guard let url = URL(string: jsonUrlString) else {return}
        URLSession.shared.dataTask(with: url) { (data, response, err) in
        guard let data = data else {return}

        do {
            let websiteDescription = try JSONDecoder().decode(WebsiteDescription.self, from: data)
            print(websiteDescription.name, websiteDescription.description, websiteDescription.courses)
            //let courses = try JSONDecoder().decode([Course].self, from: data)

            DispatchQueue.main.async {
                self.displayLabel.text = websiteDescription.name
            }

         } catch let jsonErr {
            print("Error serializing json", jsonErr)
        }

    }.resume()
}