InputStream never calls hasBytesAvailable - networking

Question

I'm trying to get iOS devices to discover each other with Bonjour and then connect with InputStream and OutputStream.
The devices can connect to each other, but sending bytes from one device's OutputStream will not trigger the "hasBytesAvailable" event on the other device.
Because I want devices to connect with multiple other devices, I've wrapped each connection in an "ASPeer" object, which I can put in an array to keep track of all my connections.
class ASPeer: NSObject {
let service: NetService
var inputStream: InputStream?
var outputStream: OutputStream?
init(_ service: NetService) {
self.service = service
}
func openStreams() {
guard let inputStream = inputStream, let outputStream = outputStream else {
fatalError("openStreams: failed to get streams!")
}
inputStream.delegate = self
inputStream.schedule(in: .current, forMode: .defaultRunLoopMode)
inputStream.open()
outputStream.delegate = self
outputStream.schedule(in: .current, forMode: .defaultRunLoopMode)
outputStream.open()
}
func closeStreams() {
guard let inputStream = inputStream, let outputStream = outputStream else {
fatalError("closeStreams: failed to get streams!")
}
inputStream.remove(from: .current, forMode: .defaultRunLoopMode)
inputStream.close()
inputStream.delegate = nil
outputStream.remove(from: .current, forMode: .defaultRunLoopMode)
outputStream.close()
outputStream.delegate = nil
}
}
extension ASPeer: StreamDelegate {
func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
switch aStream {
case inputStream!:
switch eventCode {
case .openCompleted:
print("inputOpenCompleted:")
case .hasBytesAvailable:
print("inputHasBytesAvailable:")
var readData = [UInt8](Data(capacity: 4096))
let bytesRead = inputStream!.read(&readData, maxLength: 4096)
if bytesRead > 0 {
print(String(bytes: readData, encoding: .ascii)!)
}
case .errorOccurred:
print("inputErrorOccurred")
case .endEncountered:
print("inputEndEncountered")
default:
break
}
case outputStream!:
switch eventCode {
case .openCompleted:
print("outputOpenCompleted:")
case .hasSpaceAvailable:
print("outputHasSpaceAvailable:")
case .errorOccurred:
print("outputErrorOccurred")
case .endEncountered:
print("outputEndEncountered")
default:
break
}
default:
print("got unknown stream!")
}
}
}
I've added print statements to every single "handle" event for my input and output streams. Here are the output logs when I run the app and try to get the devices to talk to each other:
Device 1
inputOpenCompleted:
outputOpenCompleted:
outputHasSpaceAvailable:
Device 2
inputOpenCompleted:
outputOpenCompleted:
outputHasSpaceAvailable:
When I try to send a message from Device 1 to Device 2, I'm expecting Device 2 to print out "inputHasBytesAvailable". However, I just get extra lines of "outputHasSpaceAvailable" from Device 1:
Device 1
inputOpenCompleted:
outputOpenCompleted:
outputHasSpaceAvailable:
outputHasSpaceAvailable: <--
outputHasSpaceAvailable: <--
Device 2
inputOpenCompleted:
outputOpenCompleted:
outputHasSpaceAvailable:
<-- I'm expecting "inputHasBytesAvailable" here!
What could the issue be? I've double checked my run loops and made sure they are correct. Also, there seems to be a bug with "getInputStream" and I made sure to call "getInputStream" on the main queue to avoid that problem. Is there something else I'm missing?
In addition, I also have a BonjourManager object that manages every one of these "ASPeer" connections. The BonjourManager is what actually creates the connections and sends writes to the OutputStreams.
class ASBonjourManager: NetServiceDelegate {
var peers = [ASPeer]()
// ... more code here but omitted
func netService(_ sender: NetService, didAcceptConnectionWith inputStream: InputStream, outputStream: OutputStream) {
if sender == advertiser {
return
}
if let peer = peers.first(where: { $0.service == sender }) {
OperationQueue.main.addOperation {
// Due to a bug <rdar://problem/15626440>, this method is called on some unspecified
// queue rather than the queue associated with the net service (which in this case
// is the main queue). Work around this by bouncing to the main queue.
assert((peer.inputStream == nil) == (peer.outputStream == nil))
if let _ = peer.inputStream, let _ = peer.outputStream {
inputStream.open()
inputStream.close()
outputStream.open()
outputStream.close()
} else {
peer.inputStream = inputStream
peer.outputStream = outputStream
peer.openStreams()
}
}
} else {
OperationQueue.main.addOperation {
let newPeer = ASPeer(sender)
sender.delegate = self
newPeer.inputStream = inputStream
newPeer.outputStream = outputStream
newPeer.openStreams()
self.peers.append(newPeer)
}
}
}
func connectTo(service: NetService) {
var inStream: InputStream?
var outStream: OutputStream?
let peer = peers.first(where: { $0.service.isEqual(service) })!
//assert(peer.inputStream == nil && peer.outputStream == nil)
if peer.inputStream != nil && peer.outputStream != nil {
return
}
if service.getInputStream(&inStream, outputStream: &outStream) {
peer.inputStream = inStream
peer.outputStream = outStream
peer.openStreams()
} else {
print("getInputStream failed!")
}
}
func sendMessage(_ service: NetService) {
let peer = peers.first(where: { $0.service.isEqual(service) })!
if peer.outputStream!.hasSpaceAvailable {
let message = Array("hello world".utf8)
peer.outputStream!.write(message, maxLength: message.count)
}
}
}