Swift 3 OutputStream hanging? - sockets

Question

I wrote a simple Swift program to write to a server; I want to send data back to back or in a loop to a server; I tried doing something simple where I can simply send a message back to back (two pieces of data) but there is a hang; that is, the server only receives the first message but not the second message; why is this?
I am using StreamDelegate in Swift 3 and I am using OutputStream write method
print("Hello, World!")
import Foundation
class Connection: NSObject, StreamDelegate {
private var inputStream: InputStream!
private var outputStream: OutputStream!
private var my_address: CFString
private var my_port: UInt32
init (address: CFString, port:UInt32) {
self.my_address = address
self.my_port = port
super.init()
}
func connect() {
print("connecting...")
var readStream: Unmanaged<CFReadStream>?
var writeStream: Unmanaged<CFWriteStream>?
CFStreamCreatePairWithSocketToHost(nil, self.my_address, self.my_port, &readStream, &writeStream)
// Documentation suggests readStream and writeStream can be assumed to
// be non-nil. It might be wise to test if either is nil
// and implement error-handling as needed.
// self.inputStream = readStream!.takeRetainedValue()
self.outputStream = writeStream!.takeRetainedValue()
// self.inputStream.delegate = self
self.outputStream.delegate = self
// self.inputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
// self.outputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
// self.inputStream.open()
self.outputStream.open()
}
func disconnect() {
self.inputStream.close()
self.outputStream.close()
}
func stream(aStream: Stream, handleEvent eventCode: Stream.Event) {
switch (eventCode){
case Stream.Event.errorOccurred:
NSLog("ErrorOccurred")
case Stream.Event.endEncountered:
NSLog("EndEncountered")
case Stream.Event.hasBytesAvailable:
NSLog("HasBytesAvaible")
var buffer = [UInt8](repeating: 0, count: 4096)
while (inputStream.hasBytesAvailable){
var len = inputStream.read(&buffer, maxLength: buffer.count)
if(len > 0){
var output = NSString(bytes: &buffer, length: buffer.count, encoding: String.Encoding.utf8.rawValue)
if (output != ""){
NSLog("server said: %#", output!)
}
} else {
print("empty string from stream")
}
}
case Stream.Event.openCompleted:
NSLog("OpenCompleted")
case Stream.Event.hasSpaceAvailable:
NSLog("HasSpaceAvailable")
default: print("default reached. unknown stream event")
}
}
func sendMessage(message: String) {
let buff = [UInt8](message.utf8)
self.outputStream.write(buff, maxLength: buff.count)
}
func getOutputStream() -> OutputStream {
return self.outputStream
}
}
var socket = Connection(address: "000.000.0.000" as CFString, port: 0000)
socket.connect()
socket.sendMessage(message: "Hey you! 1")
socket.sendMessage(message: "Hey you! 2")
\
import Darwin
import Foundation
import UIKit
import Dispatch
class ViewController: UIViewController {
#IBOutlet private weak var joystickMove: Joystick!
#IBOutlet private weak var joystickRotate: Joystick!
private var joystick = Joystick()
private var contour = Contours()
private var contour_index: Int = 0
private var socket = Connection(address: "000.000.0.000" as CFString, port: 0000)
override func viewDidLoad() {
super.viewDidLoad()
createJoystick()
createContours()
createButton()
}
private func createJoystick() {
let n: CGFloat = 100.0
let x: CGFloat = (UIScreen.main.bounds.width/2) - (n/2.0)
let y: CGFloat = UIScreen.main.bounds.height - (UIScreen.main.bounds.height/4.0)
self.joystick.frame = CGRect(x: x, y: y, width: n, height: n)
self.joystick.backgroundColor = UIColor.clear
self.joystick.substrateColor = UIColor.lightGray
self.joystick.substrateBorderColor = UIColor.gray
self.joystick.substrateBorderWidth = 1.0
self.joystick.stickSize = CGSize(width: 50.0, height: 50.0)
self.joystick.stickColor = UIColor.darkGray
self.joystick.stickBorderColor = UIColor.black
self.joystick.stickBorderWidth = 2.0
self.joystick.fade = 0.5
var packet = ""
DispatchQueue.global(qos: .userInitiated).async { // do some task
self.joystick.trackingHandler = { (data) -> () in
let power = sqrt(pow(Double(data.velocity.x), 2.0) + pow(Double(data.velocity.y), 2.0))
let theta = atan2(Double(-data.velocity.y), Double(data.velocity.x))
let degrees = theta * (180.0 / M_PI)
if degrees >= 55 && degrees <= 125 { // move forward
packet = "\(1) \(1) \(power) \(power)"
} else if degrees >= -125 && degrees <= -55 { // move backwards
packet = "\(-1) \(-1) \(power) \(power)"
} else if degrees >= -55 && degrees <= 55 { // turn right
packet = "\(1) \(-1) \(power) \(power)"
} else if (degrees >= 125 && degrees <= 180) && (degrees >= -180 && degrees <= -125) { // turn left
packet = "\(-1) \(1) \(power) \(power)"
}
self.socket.connect()
let sent = self.socket.sendMessage(message: packet)
if sent {
print("packet sent!\n \(packet)")
}
self.socket.stream(aStream: self.socket.inputStream, handleEvent: Stream.Event.hasBytesAvailable)
// self.socket.changeWhenHasBytesAvailable = { str in
// print("my-str: \(str.characters)")
// }
self.socket.disconnect()
}
}
view.addSubview(joystick)
}
private func createContours() {
let n: CGFloat = 350.0
let x: CGFloat = (UIScreen.main.bounds.width/2.0) - (n/2.0)
let y: CGFloat = UIScreen.main.bounds.height - (UIScreen.main.bounds.height/4.0) - n - 100.0
self.contour.frame = CGRect(x: x, y: y, width: n, height: n)
self.contour.backgroundColor = UIColor.clear
view.addSubview(self.contour)
}
private func createButton() {
let width: CGFloat = 150.0
let height: CGFloat = 75.0
let x: CGFloat = (UIScreen.main.bounds.width/2.0) - (width/2.0)
let y: CGFloat = UIScreen.main.bounds.height - (UIScreen.main.bounds.height/4.0) - width
let button: UIButton = UIButton(frame: CGRect(x: x, y: y, width: width, height: height))
button.backgroundColor = UIColor.blue
button.setTitle("Contour Views", for: .normal)
button.addTarget(self, action: #selector(self.buttonAction), for: .touchUpInside)
button.tag = 1
view.addSubview(button)
}
#objc private func buttonAction(sender: UIButton!) {
var btnsendtag: UIButton = sender
if btnsendtag.tag == 1 {
self.contour_index = (self.contour_index + 1) % 2
switch self.contour_index {
case 0:
for index in 0...356 {
if self.contour.distx[index] != -1 && self.contour.disty[index] != -1 {
self.contour.circles[index].alpha = 0
}
}
case 1:
for index in 0...356 {
if self.contour.distx[index] != -1 && self.contour.disty[index] != -1 {
self.contour.circles[index].alpha = 1
}
}
default:
for index in 0...356 {
if self.contour.distx[index] != -1 && self.contour.disty[index] != -1 {
self.contour.circles[index].alpha = 1
UIColor.cyan.setFill()
self.contour.lines[index].fill()
self.contour.lines[index].stroke()
}
}
}
}
}
override func viewDidAppear(_ animated: Bool) {
DispatchQueue.global(qos: .background).async { // do some task
// self.socket.connect()
// var packet = "1 1 0 0"
// let sent = self.socket.sendMessage(message: packet)
// if sent {
// print("packet sent!\n \(packet)")
// }
// self.socket.disconnect()
}
}
public func delayWithSeconds(_ seconds: Double, completion: #escaping () -> ()) {
DispatchQueue.main.asyncAfter(deadline: .now() + seconds) {
completion()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewWillDisappear(_ animated: Bool) {
// self.socket.disconnect()
}
}
\
import Foundation
class Connection: NSObject, StreamDelegate {
public var inputStream: InputStream!
private var outputStream: OutputStream!
private var my_address: CFString
private var my_port: UInt32
public var changeWhenHasBytesAvailable: ((String)->())?
init (address: CFString, port:UInt32) {
self.my_address = address
self.my_port = port
super.init()
}
public func connect() {
var readStream: Unmanaged<CFReadStream>?
var writeStream: Unmanaged<CFWriteStream>?
CFStreamCreatePairWithSocketToHost(nil, self.my_address, self.my_port, &readStream, &writeStream)
self.inputStream = readStream!.takeRetainedValue()
self.outputStream = writeStream!.takeRetainedValue()
self.inputStream.delegate = self
self.outputStream.delegate = self
self.inputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
self.outputStream.schedule(in: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
self.inputStream.open()
self.outputStream.open()
}
public func stream(aStream: Stream, handleEvent eventCode: Stream.Event) {
// DispatchQueue.global(qos: .userInitiated).async { // do some task
print("stream")
if aStream === self.inputStream {
switch eventCode {
case Stream.Event.openCompleted:
print("open")
break
case Stream.Event.errorOccurred:
print("error")
break
case Stream.Event.hasBytesAvailable:
print("available!")
// var inputBuffer = Array<UInt8>(repeating: 0, count:2048)
// self.inputStream?.read(&inputBuffer, maxLength: 2048)
// self.changeWhenHasBytesAvailable?(String(bytes: inputBuffer, encoding: String.Encoding.utf8)!)
var buffer = [UInt8](repeating: 0, count: 512)
while (self.inputStream.hasBytesAvailable){
print("before read")
var len = self.inputStream.read(&buffer, maxLength: buffer.count)
print("after read")
if(len > 0){
// var output = NSString(bytes: &buffer, length: buffer.count, encoding: String.Encoding.utf8.rawValue)
var output = NSString(bytes: &buffer, length: len, encoding: String.Encoding.utf8.rawValue)
if (output != ""){
print("output: \(output!)")
}
} else {
print("empty string from stream")
}
print("while")
}
break
default:
print("default")
break
}
}
// }
}
public func sendMessage(message: String) -> Bool {
var sent: Bool = false
let buff = [UInt8](message.utf8)
let result = self.outputStream.write(buff, maxLength: buff.count)
if result != -1 {
sent = true
}
return sent
}
public func disconnect() {
self.inputStream.close()
self.outputStream.close()
// self.inputStream.remove(from: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
// self.outputStream.remove(from: RunLoop.current, forMode: RunLoopMode.defaultRunLoopMode)
}
}
update; send works! but not receiving data?

Answer 1

Don't use a while inside the StreamDelegate when you are reading:
while (inputStream.hasBytesAvailable){
var len = inputStream.read(&buffer, maxLength: buffer.count)
...
}
Just call read. If there are more bytes, your delegate will be called again.