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.
I found a solution with handling the NSStreamEvent, which i have tried.
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()
}
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.")
}
}
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.")
}
}
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 ?
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
}
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.
Generally, I avoid using default
in switch statements for enums, since the compiler will tell you when you've missed something.