NSStreamDelegate does not receive NSStreamEvent.HasSpaceAvailable:

Question

I had code working in another project in a class with the following signature:

class ViewController: UIViewController, NSStreamDelegate, UITextFieldDelegate { 

Then I moved the connection to it of my own class, so I can reuse it in each connection:

 class XMPPConnection: NSObject, NSStreamDelegate 

When I did this, I moved all the viewDidLoad() code to init() . I also tried putting this init code in a separate function and calling this function after instantiating the class. This has not changed anything.

I can switch between two projects, old and new, just to make sure that this is not a server problem, and this confirms that it is not.

After each application launch, the result is different. It either does not call HasSpaceAvailable , but simply sits there, or there is an error (lldb) superimposed on stream 1 in my class class AppDelegate: UIResponder, UIApplicationDelegate, FBLoginViewDelegate . However, this error may be related to integration with Facebook, but there is not much to look at with lldb . However, with each launch, HasSpaceAvailable never called, unlike another project.

Here's the full NSStreamDelegate code, so there is no confusion. This class is a fairly standard connection method using XMPP.

 import UIKit import Foundation class XMPPConnection: NSObject, NSStreamDelegate { //NSObject var input : NSInputStream? var output: NSOutputStream? //let XMLStream: String = "<stream:stream xmlns:stream='http://etherx.jabber.org/streams' version='1.0' xmlns='jabber:client' to='mydomain.com' xml:lang='en' xmlns:xml='http://www.w3.org/XML/1998/namespace'>" let XMLStream: String = "<stream:stream to='mydomain.com' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0'>" var XMLAuth: String? let XMLStreamEnd: String = "</stream:stream>" let XMLResource: String = "<iq type='set' id='bind_1'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'><resource>OneSide</resource></bind></iq>" let XMLSession: String = "<iq type='set' id='sess_1'><session xmlns='urn:ietf:params:xml:ns:xmpp-session'/></iq>" let XMLStartTLS: String = "<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>"; var messagesToBeSent:[String] = [] var lastSentMessageID = 0 var lastReceivedMessageID = 0 init(facebookID: String) { super.init() let username = "[e-mail]" //should hash device ID let password = "123456" //hash it var UTF8AuthStr = "\0\(username)\0\(password)".dataUsingEncoding(NSUTF8StringEncoding) let Base64Str = UTF8AuthStr!.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.fromRaw(0)!) XMLAuth = "<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='PLAIN'>\(Base64Str)</auth>" //println(XMLAuth) self.connectToSocket("mydomain.com", port: 5222) send(self.XMLStream) //send(self.XMLStartTLS) /*send(self.XMLAuth!) send(self.XMLStream) send(self.XMLResource) send(self.XMLSession)*/ //sendMessage("hi") } func connectToSocket(host: String, port: Int) { NSStream.getStreamsToHostWithName(host, port: port, inputStream: &(self.input), outputStream: &(self.output)) self.input!.delegate = self self.output!.delegate = self self.input!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode) self.output!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode) self.input!.open() self.output!.open() println("Connected") //let bytesWritten = self.output!.write(UnsafePointer(data.bytes), maxLength: data.length) //println(bytesWritten) } //The delegate receives this message when a given event has occurred on a given stream. func stream(theStream: NSStream!, handleEvent streamEvent: NSStreamEvent) { println("Message received") switch streamEvent { case NSStreamEvent.None: println("NSStreamEvent.None") case NSStreamEvent.OpenCompleted: println("NSStreamEvent.OpenCompleted") case NSStreamEvent.HasBytesAvailable: println("NSStreamEvent.HasBytesAvailable") if let inputStream = theStream as? NSInputStream { //println("is NSInputStream") if inputStream.hasBytesAvailable { //println("hasBytesAvailable") let bufferSize = 1024 var buffer = Array<UInt8>(count: bufferSize, repeatedValue: 0) var bytesRead: Int = inputStream.read(&buffer, maxLength: bufferSize) //println(bytesRead) if bytesRead >= 0 { lastReceivedMessageID++ var output: String = NSString(bytes: &buffer, length: bytesRead, encoding: NSUTF8StringEncoding) //println("output is") println(output) } else { println("error") // Handle error } } } case NSStreamEvent.HasSpaceAvailable: println("NSStreamEvent.HasSpaceAvailable") send(nil) //send next item //send next message or //what if there is no next message to send, and instead waiting user input? case NSStreamEvent.ErrorOccurred: println("NSStreamEvent.ErrorOccurred") case NSStreamEvent.EndEncountered: println("NSStreamEvent.EndEncountered") default: println("default") } } func send(message:String?){ if (self.output!.hasSpaceAvailable){ //stream ready for input //println("true hasSpaceAvailable") var data:NSData var thisMessage:String if message == nil{ // no message specified if messagesToBeSent.count != 0{ //messages waiting to be sent thisMessage = messagesToBeSent[0] data = messagesToBeSent[0].dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)! messagesToBeSent.removeAtIndex(0) } else{ //no data to be sent //no message specified and nothing to be sent return } } else{ thisMessage = message! data = message!.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)! } //println("Sent the following") wait() let bytesWritten = self.output!.write(UnsafePointer(data.bytes), maxLength: data.length) lastSentMessageID++ //println(thisMessage) //println("Message sent to server and response is") //println(bytesWritten) //int count } else{ //steam busy println("no space available in stream") if message != nil{ messagesToBeSent.append(message!) } } } func sendMessage(message:String, from:String, to:String){ let xmlMessage = "<message to='\(to)@mydomain.com' from='\(from)@mydomain.com' type='chat' xml:lang='en'> <body>\(message)</body></message>" send(xmlMessage) } func wait() { while true { //println("waiting") if lastSentMessageID == lastReceivedMessageID { break } NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow: 0.1)); NSThread.sleepForTimeInterval(0.1) } } } 

So, I see two things that could cause this. Either move it to your class and make an instance, or change the inheritance. Reflecting on the first opportunity, I look at lines with alternating code: self.input!.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)

After checking streamStatus.toRaw() it says 1 , which is equal to NSStreamStatusOpening . I'm not sure if that will change.

Answer 1

I could reproduce the problem if XMPPConnection is stored in a local variable, for example.

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { let conn = XMPPConnection(facebookID: "...") return true } 

The instance is freed when this method returns. On the other hand, the thread delegates are still pointing to the instance, this leads to crashes. delegate property of NSStream declared as

 unowned(unsafe) var delegate: NSStreamDelegate? 

which is the equivalent of Swift "assign" aka "unsafe_unretained". Therefore, setting the delegate does not save the object, and releasing the object does not set the nil property (as for weak references).

If the instance is stored in a property, for example

 class AppDelegate: UIResponder, UIApplicationDelegate { var window: UIWindow? var conn : XMPPConnection! func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { conn = XMPPConnection(facebookID: "...") return true } // ... } 

then your code worked correctly in my test.

Answer 2

  CFStreamCreatePairWithSocketToHost(nil, serverAddress, Server, &readStream, &writeStream) CFStreamCreatePairWithSocketToHost(nil, website!.host, Server, &readStream, &writeStream) CFReadStreamSetProperty(readStream!.takeUnretainedValue(), kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue) CFWriteStreamSetProperty(writeStream!.takeUnretainedValue(), kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue) inputStream = readStream!.takeUnretainedValue(); outputStream = writeStream!.takeUnretainedValue();