Swift 函数外的作用域

Question

我有一个单例 URLSession，它正在将响应数据解析到字典中。我想在后续代码段中使用该字典中的单个值，但无法弄清楚如何将值从它当前所在的范围中传递出去。

这是现在的代码：

let task = URLSession.shared.dataTask(with: request) { data, response, error in
        guard error == nil else {
            debugPrint ("error: \(error!)")
            return
        }
        guard let content = data else {
            debugPrint("No data")
            return
        }
            guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [String: Any] else {
            debugPrint("Not containing JSON")
            return
        }
            if let idToken = json["id_token"] as? String {
                let privateToken = idToken;
                debugPrint("Gotten json response dictionary is \(idToken)")
            }
        }

        task.resume()
        return privateToken

目前 return privateToken 上有一个 IDE 错误，说我正在使用未解析的标识符：privateToken.

如何将字符串 idToken 和 return 作为 privateToken 用于其他地方？

Answer 1

你能使用像这样的完成处理程序吗：

func getPrivateToken(completion: @escaping(String) -> (), failure: @escaping (Error) -> ()) {
    URLSession.shared.dataTask(with: request) { data, response, error in
        guard error == nil else {
            debugPrint ("error: \(error!)")
            failure(error)
            return
        }
        guard let content = data else {
            debugPrint("No data")
            failure(NSError(domain: "Your error message here.", code: 401, userInfo: nil))
            return
        }
        guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [String: Any] else {
            debugPrint("Not containing JSON")
            failure(NSError(domain: "Your error message here.", code: 401, userInfo: nil))
            return
        }
        if let idToken = json["id_token"] as? String {
            completion(idToken)
            debugPrint("Gotten json response dictionary is \(idToken)")
        }
    }.resume()
}

并像这样使用它：

func exampleFunction() {
    self.getPrivateToken(completion: { (token) in
        // Do what ever you need with the token here.
        print("ID token is: \(token)")
    }) { (error) in
        // Present error here
    }
}

Swift 函数外的作用域

Swift scoping outside of a function

swift

scope

urlsession