Question

我有一个从网站上的JSON文件中获取数据的方法。当我第一次午餐app它工作得很好，但是当JSON文件中的数据更新时，我的方法仍然获取相同的数据。我必须删除app app并再次安装才能获得新数据。这是我的代码：

private func fetchSchools(){
        let url = "https://www.example.com/inc/json.txt"
        let requestURL: NSURL = NSURL(string: url)!
        let urlRequest: NSMutableURLRequest = NSMutableURLRequest(url: requestURL as URL)
        let session = URLSession.shared
        session.dataTask(with: urlRequest as URLRequest) {
            (data, response, error) -> Void in

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


            if (statusCode == 200) {
                print("Everything is fine, file downloaded successfully.")

                do {

                    let json = try JSONSerialization.jsonObject(with: data!, options: []) as? [String : AnyObject]
                    if let JSONSchools = json?["skoly"] as? [[String : AnyObject]] {

                        for school in JSONSchools {

                            if let name = school["nazev"] as? String {

                                if let city = school["mesto"] as? String {

                                    if let id = school["id"] as? String {
                                        self.schools.append(School.init(name: name, city: city, id: id))
                                       // print(name)
                                    }

                                }

                            }
                        }
                        self.fetchFinished = true
                    }

                } catch {
                    print("Error with Json: \(error)")
                }
            }
        }

        .resume()
    }

我调试了我的代码，我意识到这一点：let json = try JSONSerialization.jsonObject(with: data!, options: []) as? [String : AnyObject] 获取仍然相同的数据，因此它看起来像JSONSerialization保存第一次获取，然后不从网站获取但返回保存的值。

感谢您的帮助

修改：我将代码更改为：

func fetchSchools(completion: @escaping (String) -> ()){
        let url = "https://www.example.com/inc/json.txt"
        let requestURL: NSURL = NSURL(string: url)!
        let urlRequest: NSMutableURLRequest = NSMutableURLRequest(url: requestURL as URL)
        let session = URLSession.shared
        session.dataTask(with: urlRequest as URLRequest) {
            (data, response, error) -> Void in

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


            if (statusCode == 200) {
                print("Everything is fine, file downloaded successfully.")

                if let data = data, let jsonString = String(data: data, encoding: String.Encoding.utf8), error == nil{
                    completion(jsonString)
                } else {
                    print("error=\(error!.localizedDescription)")
                }
            }
        }

        .resume()
    }

但它没有改变我的问题。任何想法如何解决？

解决方案 最后我发现this solution，我的方法很好，但我从缓存中获取JSON，所以我必须添加这行代码来忽略缓存。

 var request = NSURLRequest(URL: requestURL, cachePolicy: .ReloadIgnoringLocalCacheData, timeoutInterval: 30)

JSON获取相同的数据

0 个答案: