ios - 使用 swift 3 从 asp.net web api 中过滤来自 JSON 的字符串

Question

我是网络开发和 Swift 的新手

我创建了一个基于 ASP.NET 的 Web API，并连接了我的 iOS 应用程序，这样我就可以执行 GET、POST、PUT、DELETE。

当我发送带有特定 ID 号的 GET 请求时 我在 Xcode 中得到如下输出:

Data:
Optional("{\"Id\":1,\"UserName\":\"codeinflash\",\"UserPassword\":\"Wldnrodxxxx\",\"UserEmail\":\"codeinflash@gmail.com\",\"Rebate\":0.00,\"MemCom\":123.44}")

这是 Swift 中的函数:

//GET /api/account/{id}
@IBAction func GetAccount(_ sender: Any) {
    let _accountIdNumber = AccountIdNumber.text
    if (_accountIdNumber!.isEmpty){
        createAlert(title: "Warning", message: "Account ID # is required")
        return
    }

    let restEndPoinst: String = "http://tresmorewebapi2.azurewebsites.net/api/account/" + _accountIdNumber!;
    guard let url = URL(string: restEndPoinst) else {
        print("Error creating URL")
        return
    }

    var urlRequest = URLRequest(url: url)
    urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
    // api key need urlRequest.setValue(<#T##value: String?##String?#>, forHTTPHeaderField: "APIKey")
    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)

    var userEmail = ""
    var rebate = ""
    var memcom = ""


    let task = session.dataTask(with: urlRequest, completionHandler:
        {
            (data, response, error) in
            print("Error:")
            print(error)
            print("response:")
            print(response)
            print("Data:")
            print(String(data: data!, encoding: String.Encoding.utf8))

//////////////I think I need logic here to filter the data
userEmail = data.substring of find emailaddress
rebate = data.substring find users' rebate
memcom = same logic
then show alert window with his info and I will show his info on next page which is a Dashboard page view

    })

    task.resume()

}

老实说，我不确定数据是 JSON 数据，但 Xcode 中的输出是字符串。

我的目的是获取用户的数据并将其存储在局部变量中，这些局部变量将它们传递给 ios Swift 中的下一个 View (仪表板)。

谢谢!

已添加 这是在快速登录功能中从 web api 获取数据的任务

let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)

    var userEmail = ""
    var rebate = ""
    var memcom = ""

    let task = session.dataTask(with: urlRequest, completionHandler:
        {
            (data: Data?, response: URLResponse?, error: Error?) in
            print("Error:")
            print(error)
            print("response:")
            print(response)
            print("Data:")
            print(String(data: data!, encoding: String.Encoding.utf8))

            let json = try? JSONSerialization.jsonObject(with: data!) as! [String: AnyObject] ?? [:];
            userEmail = json?["UserEmail"] as? String ?? ""
            createAlert(title: "Got User Eamil Address!", message: userEmail)
    })

    task.resume()

但是我在警报 View 中什么也看不到。我测试过的警报 View 工作正常。

这是我在 Swift 中的 createAlert 函数

func createAlert(title:String, message:String){
    let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (anction) in
        alert.dismiss(animated: true, completion: nil)}))

    self.present(alert, animated: true, completion: nil)
}

Answer 1

您已经在评论中找到了答案，但这种方式不那么“敏捷”，对于 Swift 新手来说更具可读性(注意并尝试理解正在发生的事情以及如何使它更紧凑):

do {

    guard let unwrappedData = data else{
        //data is nil - handle case here
        return //exit scope
    }
    guard let dictionary = try JSONSerialization.jsonObject(with: unwrappedData) as? [String:AnyObject] else {
        //you cannot cast this json object to dictionary - handle case here
        return //exit scope
    }

    userEmail = dictionary["UserEmail"]
    DispatchQueue.main.async { [weak self] in
        self?.createAlert(title: "Got User Eamil Address!", message: userEmail)
    }
} catch _ {
    //handle error
}