[英]Use NSOutputstream and NSInputstream to write and read every interval
I'm trying to use NSOutputstream and NSInputstream to write and read every interval, say 5 seconds. 我正在尝试使用NSOutputstream和NSInputstream写入和读取每个间隔(例如5秒)。 This is to communicate with a C# program on windows in P2P fashion. 这是为了以P2P方式与Windows上的C#程序进行通信。
I want to use NSOutputstream to send the C# program a request every 5 seconds and then NSInputstream will read the response from the C# program. 我想使用NSOutputstream每5秒向C#程序发送一个请求,然后NSInputstream将从C#程序读取响应。
Currently I have: 目前我有:
class Connection : NSObject, NSStreamDelegate {
var serverAddress: CFString
let serverPort: UInt32 = 11000
private var inputStream: NSInputStream!
private var outputStream: NSOutputStream!
init(serverAddress: CFString) {
self.serverAddress = serverAddress
}
func connect() {
print("connecting...")
var readStream: Unmanaged<CFReadStream>?
var writeStream: Unmanaged<CFWriteStream>?
CFStreamCreatePairWithSocketToHost(nil, self.serverAddress, self.serverPort, &readStream, &writeStream)
self.inputStream = readStream!.takeRetainedValue()
self.outputStream = writeStream!.takeRetainedValue()
self.inputStream.delegate = self
self.outputStream.delegate = self
self.inputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
self.outputStream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
self.inputStream.open()
self.outputStream.open()
print("connected...")
}
func disconnect() {
self.inputStream.close()
self.outputStream.close()
}
func receive() -> String {
let data: NSData = "GiveMeCurrentTime".dataUsingEncoding(NSUTF8StringEncoding)!
let bytesWritten = outputStream.write(UnsafePointer<UInt8>(data.bytes), maxLength: data.length)
print("wrote \(bytesWritten) bytes")
var buffer = [UInt8](count: 100, repeatedValue: 0)
inputStream.read(&buffer,maxLength: buffer.count)
let currentTime = String.fromCString(UnsafePointer(buffer))
print("Data received is \(currentTime)")
return currentTime
}
func stream(stream: NSStream, handleEvent eventCode: NSStreamEvent) {
//print("stream event")
if stream === inputStream {
switch eventCode {
case NSStreamEvent.ErrorOccurred:
print("input: ErrorOccurred: \(stream.streamError?.description)")
case NSStreamEvent.OpenCompleted:
print("input: OpenCompleted")
case NSStreamEvent.HasBytesAvailable:
print("input: HasBytesAvailable")
break;
case NSStreamEvent.HasSpaceAvailable:
break;
default:
print("\(eventCode)")
break
}
}
else if stream === outputStream {
switch eventCode {
case NSStreamEvent.ErrorOccurred:
print("output: ErrorOccurred: \(stream.streamError?.description)")
case NSStreamEvent.OpenCompleted:
print("output: OpenCompleted")
case NSStreamEvent.HasSpaceAvailable:
print("output: HasSpaceAvailable")
// Here you can write() to `outputStream`
break;
default:
print("\(eventCode)")
break
}
}
}
The connection class will be used as below with NSTimer and NSRunLoop: 该连接类将与NSTimer和NSRunLoop一起使用,如下所示:
func start(ipAddress ipAddress: String) {
self.conn = Connection(serverAddress: ipAddress)
self.conn!.connect()
self.sendTimer = NSTimer.scheduledTimerWithTimeInterval(5.0, target: self, selector: "getTimeAndUpdateUI", userInfo: nil, repeats: true)
NSRunLoop.currentRunLoop().addTimer(self.sendTimer!, forMode: NSDefaultRunLoopMode)
}
}
func getTimeAndUpdateUI() {
let time = self.conn!.receive()
self.timeLabel.text = "Current time is \(time)"
}
The first run is always okay - I can get the current time and display it correctly. 第一次运行总是可以的-我可以获取当前时间并正确显示它。 But the subsequent runs never succeed. 但是随后的运行永远不会成功。 The output stream cannot write any byte out. 输出流不能写出任何字节。 And the input stream got the following error when reading: 并且读取时输入流出现以下错误:
ErrorOccurred: Optional("Error Domain=NSPOSIXErrorDomain Code=32 \\"Broken pipe\\"") 错误发生:可选(“错误域= NSPOSIXErrorDomain代码= 32 \\“断管\\”“)
I've tried searching for a long time but couldn't find a solution. 我尝试搜索了很长时间,但是找不到解决方案。 Any help would be much appreciated. 任何帮助将非常感激。
Looks like NSInputStream and NSOutputStream are not supposed to be re-used after a stream finishes. 看起来在流完成之后,不应重新使用NSInputStream和NSOutputStream。 I fix the problem by changing the code to below: 我通过将代码更改为以下来解决此问题:
func start(ipAddress ipAddress: String) {
self.conn = Connection(serverAddress: ipAddress)
self.sendTimer = NSTimer.scheduledTimerWithTimeInterval(5.0, target: self, selector: "getTimeAndUpdateUI", userInfo: nil, repeats: true)
NSRunLoop.currentRunLoop().addTimer(self.sendTimer!, forMode: NSDefaultRunLoopMode)
}
func getTimeAndUpdateUI() {
self.conn!.connect()
let time = self.conn!.receive()
self.timeLabel.text = "Current time is \(time)"
self.conn!.disconnect()
}
Every time iOS poll the server for information, it recreates an instance of NSInputStream and NSOutputStream. 每次iOS轮询服务器以获取信息时,它都会重新创建NSInputStream和NSOutputStream的实例。
Any suggestion to improve is welcome. 欢迎提出任何改进建议。 Thanks. 谢谢。
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