在Swift中从NSInputStream接收数据 [英] Receiving Data from NSInputStream in Swift

问题描述

我尝试在Swift中使用NSOutputStream和NSInputStream发送和接收数据.数据发送工作正常，但是我对接收有一些疑问.

I try to send and receive data with NSOutputStream and NSInputStream in Swift. The sending of data is working well, but i have some questions about the receiving.

我找到了一种尝试处理NSStreamEvent的解决方案.

I found a solution with handling the NSStreamEvent, which i have tried.

首先，我要初始化连接的功能:

First of all my function for initializing the connection:

func initNetworkCommunication(){  
    var host : CFString = "127.0.0.1"
    var port : UInt32 = 7001
    var readstream : Unmanaged<CFReadStream>?
    var writestream : Unmanaged<CFWriteStream>?
    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host, port, &readstream, &writestream)

    inputstream = readstream!.takeRetainedValue()
    outputstream = writestream!.takeRetainedValue()

    inputstream.delegate = self
    outputstream.delegate = self


    inputstream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
    outputstream.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

    inputstream.open()
    outputstream.open()   
}

这部分正在工作.我已经将委托设置为self，所以我应该能够处理此类中的NSStreamEvents.

This part is working. I have set the delegates to self, so i should be able to handle the NSStreamEvents in this class.

func stream(aStream: NSStream, handleEvent eventCode: NSStreamEvent) {
    switch (eventCode){
    case NSStreamEvent.OpenCompleted:
        NSLog("Stream opened")
        break
    case NSStreamEvent.HasBytesAvailable:
        NSLog("HasBytesAvailable")
        break
    case NSStreamEvent.ErrorOccurred:
         NSLog("ErrorOccurred")
        break
    case NSStreamEvent.EndEncountered:
        NSLog("EndEncountered")
        break
    default:
        NSLog("unknown.")
    }
}

据我了解，每次到达某些数据时，它应该打印"HasBytesAvaible"，但它打印未知".每次.所以我玩了一下，它可以解决这个问题:

In my understanding everytime when some data arrives, it should print "HasBytesAvaible", but it printed "unknown." everytime. So i played around a bit and it worked with this:

func stream(aStream: NSStream, handleEvent eventCode: NSStreamEvent) {

    var buffer = [UInt8](count: 4096, repeatedValue: 0)
    while (inputstream.hasBytesAvailable){
        let result: Int = inputstream.read(&buffer, maxLength: buffer.count)
    }

    switch (eventCode){
    case NSStreamEvent.OpenCompleted:
        NSLog("Stream opened")
        break
    case NSStreamEvent.HasBytesAvailable:
        NSLog("HasBytesAvailable")
        var output = NSString(bytes: &buffer, length: buffer.count, encoding: NSUTF8StringEncoding)
        NSLog("output: %@", output)
        receiveMessage(output) //only adds the message to an array
        break
    case NSStreamEvent.ErrorOccurred:
        NSLog("ErrorOccurred")
        break
    case NSStreamEvent.EndEncountered:
          NSLog("EndEncountered")
        break
    default:
        NSLog("unknown.")
    }
}

它正以这种方式工作，但是我想问你这是否是正确的方式?此时的最佳实践是什么?

It's working this way, but i wanted to ask you whether this is the right way ? What is the best practice at this point ?

更新 几周前，我再次进行了研究，找出了自己的错误.这是工作代码.

UPDATE I worked on it again a few weeks ago and figured out my mistakes. So here is the working code.

func stream(aStream: NSStream, handleEvent eventCode: NSStreamEvent) {
        switch (eventCode){
    case NSStreamEvent.ErrorOccurred:
        NSLog("ErrorOccurred")
        break
    case NSStreamEvent.EndEncountered:
        NSLog("EndEncountered")
        break
    case NSStreamEvent.None:
        NSLog("None")
        break
    case NSStreamEvent.HasBytesAvailable:
        NSLog("HasBytesAvaible")
        var buffer = [UInt8](count: 4096, repeatedValue: 0)
        if ( aStream == inputstream){

            while (inputstream.hasBytesAvailable){
                var len = inputstream.read(&buffer, maxLength: buffer.count) 
                if(len > 0){
                    var output = NSString(bytes: &buffer, length: buffer.count, encoding: NSUTF8StringEncoding) 
                    if (output != ""){
                        NSLog("server said: %@", output!)
                    }
                }
            } 
        }
        break
    case NSStreamEvent.allZeros:
        NSLog("allZeros")
        break
    case NSStreamEvent.OpenCompleted:
        NSLog("OpenCompleted")
        break
    case NSStreamEvent.HasSpaceAvailable:
        NSLog("HasSpaceAvailable")
        break
  }

推荐答案

您遗漏了事件hasSpaceAvailable，我希望该事件在显示未知"时发生.告诉您已经准备好接收更多数据.

You're missing the event hasSpaceAvailable, which I expect is occurring when it says "unknown". It's telling you that it is ready to receive more data.

通常，我会避免在switch语句中为枚举使用default，因为编译器会在您错过某些内容时告诉您.

Generally, I avoid using default in switch statements for enums, since the compiler will tell you when you've missed something.

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