我可以通过 NSURLSession 在 Swift 中以某种方式执行同步 HTTP 请求吗

我可以通过某种方式进行同步 HTTP 请求吗NSURLSession在斯威夫特？

我可以通过以下代码执行异步请求：

if let url = NSURL(string: "https://2ch.hk/b/threads.json") {
            let task = NSURLSession.sharedSession().dataTaskWithURL(url) {
                (data, response, error) in

                var jsonError: NSError?
                let jsonDict = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &jsonError) as [String: AnyObject]
                if jsonError != nil {
                    return
                }

                // ...
            }
            task.resume()
        }

但是同步请求呢？

您可以使用此 NSURLSession 扩展来添加同步方法：

extension NSURLSession {
    func synchronousDataTaskWithURL(url: NSURL) -> (NSData?, NSURLResponse?, NSError?) {
        var data: NSData?, response: NSURLResponse?, error: NSError?

        let semaphore = dispatch_semaphore_create(0)

        dataTaskWithURL(url) {
            data = $0; response = $1; error = $2
            dispatch_semaphore_signal(semaphore)
        }.resume()

        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER)

        return (data, response, error)
    }
}

Swift 3 更新：

extension URLSession {
    func synchronousDataTask(with url: URL) -> (Data?, URLResponse?, Error?) {
        var data: Data?
        var response: URLResponse?
        var error: Error?

        let semaphore = DispatchSemaphore(value: 0)

        let dataTask = self.dataTask(with: url) {
            data = $0
            response = $1
            error = $2

            semaphore.signal()
        }
        dataTask.resume()

        _ = semaphore.wait(timeout: .distantFuture)

        return (data, response, error)
    }
}