NSOutputStream blocking, HasBytesAvailable event was not triggered - ios

Question

I am trying to create custom framework that will deal with ExternalAccessory.framework to do read/write operation with the connected accessory.
I can able to create a session and open the device to do read/write operations.
Problem i am facing was, when i try to write data using NSOutputStream.write from the application, data successfully received by the accessory but after that UI was not responding and data returned byte accessory was not received by the app(HasBytesAvailable was not called)
Here my UIViewController.swift
let sessionHandler = SessionHandler().sharedController()
in ViewDidLoad()
let runLoop = NSRunLoop.currentRunLoop()
sessionHandler.openDeviceWithProtocolString(runLoop)
#IBAction calling sessionHandler._WriteData()
This SessionHandler class was in inside my custom SDK (custom framework)
Here my SessionHandler Class
import UIKit
import ExternalAccessory
public class SessionHandler: NSObject, NSStreamDelegate {
var readData: NSMutableData?
var writeData: NSMutableData?
var _session: EASession?
public func sharedController() -> SessionHandler{
var sessionController: SessionHandler?
if sessionController == nil {
sessionController = SessionHandler()
}
return sessionController!
}
func getConnectedAccessoris() -> Array<EAAccessory>{
let accessories : Array<EAAccessory> = EAAccessoryManager.sharedAccessoryManager().connectedAccessories
return accessories
}
public func openDeviceWithProtocolString(_runLoop: NSRunLoop){
print("Inside openDeviceWithProtocolString")
let _accessories = getConnectedAccessoris()
var _accessory: EAAccessory?
for acsy in _accessories {
if acsy.protocolStrings.contains("my.protocol.string") {
_accessory = acsy
}
}
if _accessory != nil {
_session = EASession(accessory: _accessory!, forProtocol: "my.protocol.string")
print("EASession create :: \(_session)")
if _session != nil {
_session?.inputStream?.delegate = self
_session?.inputStream?.scheduleInRunLoop(_runLoop, forMode: NSDefaultRunLoopMode)
_session?.inputStream?.open()
print("Input stream Opened")
_session?.outputStream?.delegate = self
_session?.outputStream?.scheduleInRunLoop(_runLoop, forMode: NSDefaultRunLoopMode)
_session?.outputStream?.open()
print("Output Stream Opened")
}else {
print("SessionHandler : session nil")
}
}
}
public func _readData() {
print("Trying to read data")
let INPUT_BUFFER_SIZE = 65536
let buf = UnsafeMutablePointer<UInt8>.alloc(INPUT_BUFFER_SIZE)
while ((_session?.inputStream?.hasBytesAvailable) != nil) {
let bytesRead = _session?.inputStream?.read(buf, maxLength: INPUT_BUFFER_SIZE)
if readData == nil {
readData = NSMutableData()
}
readData?.appendBytes(buf, length: bytesRead!)
}
if readData != nil {
let data: NSData = readData!
let count = data.length / sizeof(UInt8)
// create an array of Uint8
var array = [UInt8](count: count, repeatedValue: 0)
// copy bytes into array
data.getBytes(&array, length:count * sizeof(UInt8))
print("Data Received :: \(array)")
validateData(array)
}
}
public func _writeData() {
while _session?.outputStream?.hasSpaceAvailable != nil && writeData?.length > 0 {
print("Writting bytes :: \(writeData?.bytes)")
let bytesWritten = _session?.outputStream?.write(UnsafePointer<UInt8>((writeData?.bytes)!), maxLength: (writeData?.length)!)
print("written bytes : \(bytesWritten)")
if bytesWritten == -1 {
//Write error
print("written error")
break
}else if bytesWritten > 0 {
print("Written success")
validateData(writeData)
writeData?.replaceBytesInRange(NSMakeRange(0, bytesWritten!), withBytes: nil, length: 0)
}
}
}
func stream(aStream: NSStream, handleEvent eventCode: NSStreamEvent) {
switch (eventCode) {
case NSStreamEvent.None:
print("NSStream None")
break
case NSStreamEvent.OpenCompleted:
print("Open Completed")
break
case NSStreamEvent.HasBytesAvailable:
print("Has Bytes Available")
_readData()
break
case NSStreamEvent.HasSpaceAvailable:
print("Hase space Available")
_writeData()
break
case NSStreamEvent.ErrorOccurred:
print("Error occurred")
break
case NSStreamEvent.EndEncountered:
print("End Encountered")
break
default:
print("No stream event")
break
}
}
}
Thanks in Advance..

Answer 1

sessionHandler.openDeviceWithProtocolString(runLoop)
Isn't it supposed to be called on another thread?

Answer 2

I'm sure this is too late, but while ((_session?.inputStream?.hasBytesAvailable) != nil) looks like an infinite loop to me, because true/false will always be != nil.