我可以通过 Swift 中的 NSURLSession 以某种方式执行同步 HTTP 请求吗 [英] Can I somehow do a synchronous HTTP request via NSURLSession in Swift

问题描述

我可以在 Swift 中通过 NSURLSession 以某种方式执行同步 HTTP 请求吗?

Can I somehow do a synchronous HTTP request via NSURLSession in Swift?

我可以通过以下代码进行异步请求:

I can do an asynchronous request via the following code:

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?

推荐答案

你可以使用这个 NSURLSession 扩展来添加同步方法:

You can use this NSURLSession extension to add a synchronous method:

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)
    }
}

这篇关于我可以通过 Swift 中的 NSURLSession 以某种方式执行同步 HTTP 请求吗的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！