How to make synchronous url requests with swift 3

import Foundation

class SyncRequest : NSOperation {

 var socket:GCDAsyncSocket! = nil
 var msgData:NSData! = nil

 override var concurrent: Bool {
   return false
 }

 override var asynchronous: Bool {
   return false
 }

 private var _executing: Bool = false
 override var executing: Bool {
    get {
        return _executing
    }
    set {
        if (_executing != newValue) {
            self.willChangeValueForKey("isExecuting")
            _executing = newValue
            self.didChangeValueForKey("isExecuting")
        }
    }
}

private var _finished: Bool = false;
override var finished: Bool {
    get {
        return _finished
    }
    set {
        if (_finished != newValue) {
            self.willChangeValueForKey("isFinished")
            _finished = newValue
            self.didChangeValueForKey("isFinished")
        }
    }
}

/// Complete the operation
func completeOperation() {
    executing = false
    finished  = true
}

override func start() {
    if (cancelled) {
        finished = true
        return
    }

    executing = true

    main()
}


 override func main() -> (){
    println("starting...")

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "didReadData:", name: "DidReadData", object: nil)

    sendData()
}


    func sendData() {
        socket.writeData(msgData, withTimeout: -1.0, tag: 0)
        println("Sending: \(msgData)")
        socket.readDataWithTimeout(-1.0, tag: 0)
    }


    func didReadData(notif: NSNotification) {
        println("Data Received!")

        NSNotificationCenter.defaultCenter().removeObserver(self, name: "DidReadData", object: nil)

        completeOperation()

    }

}

// sync the request to the controller
let queue = NSOperationQueue() // sync request queue
let requestOperation = SyncRequest()
requestOperation.socket = socket // pass the socket  to send through
requestOperation.msgData = msgData // pass the msgData to send
queue.maxConcurrentOperationCount = 1
queue.addOperation(requestOperation)

public func socket(socket : GCDAsyncSocket!, didReadData data:NSData!, withTag tag:Int){

  ...
  NSNotificationCenter.defaultCenter().postNotificationName("DidReadData", object: data)
  ...

}

for year in years[1:]:
    for state in states[1:]:
        yield Request(
            # ...,
            callback=self.parse_city, 
            meta={'cookiejar': state} 
        )