Synchronous HTTP request in

sendSynchronousRequest.swift

// known-good: 8.3.2, Swift 3
/**
Sometimes you just want to launch a synchronous HTTP request for some JSON, damnit.

Other approaches here: https://github.com/algal/SynchronousDownloadPlayground

*/

extension URLSession {
  func sendSynchronousRequest(_ request:URLRequest,
                              timeout:TimeInterval = -1)  -> (Data?,URLResponse?,NSError?)?
  {
    let sem = DispatchSemaphore(value: 0)
    var result:(Data?,URLResponse?,NSError?)
    let task = self.dataTask(with: request, completionHandler: { (theData, theResponse, theError) in
      result = (theData,theResponse,theError as NSError?)
      sem.signal()
    })
    task.resume()
    let t = timeout == -1 ? DispatchTime.distantFuture : DispatchTime.now() + Double(Int64(NSEC_PER_SEC) * Int64(timeout)) / Double(NSEC_PER_SEC)
    let noTimeout = sem.wait(timeout: t)
    if noTimeout == .timedOut {
      return nil
    }
    return result
  }

  /// Synchronously launches a URL request, returning JSON or nil on timeout
  func sendSynchronousRequest(_ request:URLRequest,
                              timeout:TimeInterval = -1)  -> [String:Any]?
  {
    guard
      let result:(Data?,URLResponse?,NSError?) = sendSynchronousRequest(request,timeout:timeout),
      let data = result.0,
      let jsonObject = try? JSONSerialization.jsonObject(with: data, options: []),
      let jsonDict = jsonObject as? [String:Any]
      else { return nil }

    return jsonDict
  }
}