SWIFT 可解码数据传输

Question

我在 viewController 中有一个 usernameTextField，我在其中输入用户名和按钮 searchTapped，代码如下：

@IBAction func searchTapped(_ sender: UIButton) {
        guard let username = usernameTextField.text, username != "" else {
            displayWarningLabel(withText: "Information is incorrect")
            return
        }

        guard let gitUrl = URL(string: "https://api.github.com/users/\(username)/gists") else { return }
        URLSession.shared.dataTask(with: gitUrl) { (data, response, error) in

            guard let data = data else { return }
            guard error == nil else { return }
            do {
                let gitData = try JSONDecoder().decode([Gists].self, from: data)
                DispatchQueue.main.async {
                    self.gists = gitData
                }
            } catch let error {
                print(error)
            }
            }.resume()

        performSegue(withIdentifier: "GistsSegue", sender: nil)
    }

从 json 获取数据后，我想将数据保存到此方法之外的数组 gists 中，但这不会发生。

 var gists = [Gists]()

可能是什么问题？

以防万一，这是我解析 json 的模型：

struct Gists: Codable {
    var description: String?
    var files: [String: DetailGist]
}

struct DetailGist: Codable {
    var filename: String?
    var raw_url: String?
}

Answer 1

self.gists = gitData 正在被调用，但在您调用 performSegue 之后很久才会调用它。这就是异步数据访问的本质。

只需将您的performSegue 调用移动到您设置self.gists 之后。

DispatchQueue.main.async {
    self.gists = gitData
    performSegue(withIdentifier: "GistsSegue", sender: nil)
}