How to read data from NSInputStream explicitly in swift?

Question

I am using a socket connect in my application.

Here's my SocketConnection.swift

    init(host: String, port:UInt32){
        self.host = host
        self.port = port
        self.status = false
        output = ""
        super.init()
    }

    func stream(aStream: NSStream, handleEvent aStreamEvent: NSStreamEvent) {
        switch aStreamEvent {

        case NSStreamEvent.OpenCompleted:
            break

        case NSStreamEvent.HasBytesAvailable:

            break

        case NSStreamEvent.HasSpaceAvailable:
            break

        case NSStreamEvent.EndEncountered:

//            aStream.close()
            aStream.removeFromRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
            break

        case NSStreamEvent.None:

            break

        case NSStreamEvent.ErrorOccurred:

            break

        default:
            println("# something weird happend")
            break
        }
    }

    func connect() {
        println("# connecting to \(host):\(port)")
        var cfReadStream : Unmanaged<CFReadStream>?
        var cfWriteStream : Unmanaged<CFWriteStream>?

        CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host, port, &cfReadStream, &cfWriteStream)
        inputStream = cfReadStream!.takeRetainedValue()
        outputStream = cfWriteStream!.takeRetainedValue()

        inputStream!.delegate = self
        outputStream!.delegate = self

        inputStream!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
        outputStream!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

        inputStream!.open()
        outputStream!.open()
    }


    func read(){  
        var buffer = [UInt8](count: bufferSize, repeatedValue: 0)
        output = ""
        while (self.inputStream!.hasBytesAvailable){
            var bytesRead: Int = inputStream!.read(&buffer, maxLength: buffer.count)
            if bytesRead >= 0 {
                output += NSString(bytes: UnsafePointer(buffer), length: bytesRead, encoding: encoding)! as String
            } else {
                println("# error")
            }
            println("> \(output)")
        }
    }

    func send(message:String){        
            let data:NSData = message.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
            let bytesWritten = self.outputStream!.write(UnsafePointer(data.bytes), maxLength: data.length)
            println("< send to \(host)")

    }

In my ViewController.swift, I am connecting to the server like this

var socketConnection = SocketConnection(host: _ip, port: _port) 
socketConnection.connect() 
socketConnection.send(urlString) 
socketConnection.read()

Now I can send my url string via socket but when I am reading explicitly I am not getting the data from the server if I call the same read function from the NSStreamEvent.HasBytesAvailable case it printing the server response.. but how can I trigger the event queue?

I want to call this socketConnection.read() explicitly.. How can I do that?

After 2 sec of connection, its closes the connection channel, I want to keep alive my connection until I close.

Help me out from this problem.

Thanks

Don't schedule your stream if you want to read explicitly. But it may result blocking main thread. — Satachito, May 04 '15 at 14:50

score 1 · Answer 1 · answered Sep 06 '18 at 09:46

Change your read() as below and then call read() func in case NSStreamEvent.HasBytesAvailable:

private func read(stream: InputStream) {
    let maxReadLength = 1024
    let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: maxReadLength)
    while stream.hasBytesAvailable {
        let numberOfBytesRead = inputStream?.read(buffer, maxLength: maxReadLength)

        if numberOfBytesRead! < 0 {
            if let _ = inputStream?.streamError {
                break
            }
        }

        if let message = processedMessageString(buffer: buffer, length: numberOfBytesRead!) {
            delegate?.receivedMessage(message: message)
        }
    }
}

score 0 · Answer 2 · answered Jan 30 '19 at 06:00

You do not need to call read functionality explicitly. Change your read func as below and call in case case Stream.Event.hasBytesAvailable:.

func read(stream: InputStream) {
let maxReadLength = 1024
var buffer = [uint8](repeating: 0, count: maxReadLength)
while stream.hasBytesAvailable {
    let numberOfBytesRead : Int = stream.read(&buffer, maxLength: maxReadLength)
    if numberOfBytesRead < 0 {
        if let _ = stream.streamError {
            break
        }
    }

    if let message = processedMessageString(buffer: buffer, length: numberOfBytesRead) {
        delegate?.receivedMessage(message: message)
    }
}}

If you want to call read() explicitly then you need to pass the stream as parameters and call the read function in ViewController class—

socketConnection.read(stream)

How to read data from NSInputStream explicitly in swift?

2 Answers2