Question

我无法使用本质上下载JSON数据并解析它的代码，以返回returnInfo。当我打印信息它是完整的但是当它返回时，返回结构默认值。不确定我做错了什么帮助会受到高度赞赏！

如果您需要任何其他信息，请告诉我，我很乐意提供。

import Foundation

struct stockData {
   var name: String = ""
   var askPrice: String = ""
   var percentageChange: String = ""
}

class stockinfo {

    init () {

    }

    func getInfo (stock: String) -> stockData{

            let stockSymbol = stock // Sets stock symbol
            var returnInfo = stockData()

            // Configuration for request and starts the connection

        let requestURL: NSURL = NSURL(string: "https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quotes%20where%20symbol%20in%20(%22" + stockSymbol + "%22)&env=store://datatables.org/alltableswithkeys&format=json")!
        let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL)
        let session = NSURLSession.sharedSession()
        let task = session.dataTaskWithRequest(urlRequest) {
            (data, response, error) -> Void in

            let httpResponse = response as! NSHTTPURLResponse
            let statusCode = httpResponse.statusCode

            if (statusCode == 200) {
                print("JSON File Downloaded Successfully")

                do{

                    let json = try NSJSONSerialization.JSONObjectWithData(data!, options:.AllowFragments)

                    // Parses out the JSON Query into data to be assigned to a variable and returned

                    let query: NSDictionary = json["query"] as! NSDictionary
                    let results: NSDictionary = query["results"] as! NSDictionary
                    let quote: NSDictionary = results["quote"] as! NSDictionary
                    let companyName: String = quote["Name"] as! String
                    let askPrice: String = quote["Ask"] as! String
                    let percentageChange: String = quote["ChangeinPercent"] as! String

                    // Places JSON data into return struct
                    print(companyName)
                    print(askPrice)
                    print(percentageChange)

                    returnInfo.name = companyName
                    returnInfo.askPrice = askPrice
                    returnInfo.percentageChange = percentageChange

                } catch {
                    print("Error with Json: \(error)")
                }
            }
        }
        task.resume()
        return returnInfo
    }
}

Answer 1

您需要一个完成处理程序来等待async调用dataTaskWithRequest完成。修改您的代码，如：

func getInfo (stock: String, completion: (cName: String, price: String, percentChange: String) -> ()) -> stockData{

//your code
let companyName: String = quote["Name"] as! String
                let askPrice: String = quote["Ask"] as! String
                let percentageChange: String = quote["ChangeinPercent"] as! String


                // Places JSON data into return struct
                print(companyName)
                print(askPrice)
                print(percentageChange)
             completion(cName: companyName, price: askPrice, percentChange: percentageChange)

}
//your code

然后，无论何时你想打电话，主要是按下按钮后，如果你喜欢viewDidLoad，请执行此操作：

getInfo("your string") {(name, price, change) in
///use the three values how you want.
}

使用Swift返回使用自定义数据类型的JSON数据时遇到问题

1 个答案: