iOS Synchronous HTTP Request

Generally HTTP Requests are processed asynchronously, but sometimes we need them to be processed synchronously. However, URLSession and Alamofire do not provide synchronous methods.

Since they only provide asynchronous methods, we can only wrap asynchronous methods to synchronous methods. The trick is to use a semaphore to wait for HTTP Requests finished.

func syncRequest(_ url: String, method: Method) -> (Data?, Error?) {
    var data: Data?
    var error: Error?

    let url = URL(string: url)!
    var request = URLRequest(url: url)
    request.httpMethod = method.rawValue

    let semaphore = DispatchSemaphore(value: 0)

    let dataTask = URLSession.shared.dataTask(with: request) {
        data = $0
        error = $2

        semaphore.signal()
    }
    dataTask.resume()

    _ = semaphore.wait(timeout: .distantFuture)

    return (data, error)
}