swift - 快速获取在线时间

Question

我的应用程序要求用户在线，并且即使用户更改日期，我也会尝试获取服务器时间。我找到了这段代码，它仅在我第一次运行该应用程序时才有效。然后下次它卡住时我必须更改网站。每次我更改网站时，它都会立即获取日期和时间，之后我会不断获得相同的准确时间。

代码:

func getTimeFromServer(completionHandler:@escaping (_ getResDate: Date?) -> Void){
    let url = URL(string: "https://www.apple.com")
    let task = URLSession.shared.dataTask(with: url!) {(data, response, error) in
        let httpResponse = response as? HTTPURLResponse
        if let contentType = httpResponse!.allHeaderFields["Date"] as? String {
            //print(httpResponse)
            let dFormatter = DateFormatter()
            dFormatter.dateFormat = "EEE, dd MMM yyyy HH:mm:ss z"
            let serverTime = dFormatter.date(from: contentType)
            completionHandler(serverTime)
        }
    }
    task.resume()
}

Answer 1

最好使用 NTP 服务器，但尝试使用以下内容，这会忽略缓存:

func getTimeFromServer(completionHandler:@escaping (_ getResDate: Date?) -> Void){
    let url = URL(string: "https://www.apple.com")
    let urlRequest = URLRequest(url: url!, cachePolicy: .reloadIgnoringLocalCacheData, timeoutInterval: 20)
    let task = URLSession.shared.dataTask(with: urlRequest) {(data, response, error) in
        let httpResponse = response as? HTTPURLResponse
        if let contentType = httpResponse!.allHeaderFields["Date"] as? String {
            //print(httpResponse)
            let dFormatter = DateFormatter()
            dFormatter.dateFormat = "EEE, dd MMM yyyy HH:mm:ss z"
            let serverTime = dFormatter.date(from: contentType)
            completionHandler(serverTime)
        }
    }
    task.resume()
}