Swift 2 - iOS - 发送回原始线程

Question

所以我有一个应用程序,它触发一系列异步事件,然后将结果写入缓冲区.问题是我希望缓冲区同步写入(在产生异步进程的线程中)

骨架代码就是这样

let Session = NSURLSession.sharedSession()
let TheStack = [Structure]()
//This gets called asynchronously, e.g. in threads 3,4,5,6,7
func AddToStack(The Response) -> Void { 
   TheStack.insertAt(Structure(The Response), atIndex: 0))
   if output.hasSpaceAvailable == true {
      // This causes the stream event to be fired on mutliple threads
      // This is what I want to call back into the original thread, e.g. in thread 2
      self.stream(self.output, handleEvent: NSStreamEvent.hasSpaceAvailable) 
   }
}

// This is in the main loop, e.g. thread 2
func stream(aStream: NSStream, handleEvent: NSStreamEvent) {

   switch(NSStreamEvent) {

      case NSStreamEvent.OpenCompleted:
          // Do some open stuff
      case NSStreamEvent.HasBytesAvailable:
          Session.dataTaskWithRequest(requestFromInput, completionHandler: AddToStack)
      case NSStreamEvent.HasSpaceAvailable:
          // Do stuff with the output
      case NSStreamEvent.CloseCompleted:
          // Close the stuff
   }
}

问题是调用的线程dataTaskWithRequest是在线程中,比如说3.完成处理程序在许多不同的线程中触发并导致case NSStreamEvent.HasSpaceAvailable:在线程3中运行,以及它们存在的所有线程.

我的问题是:如何self.stream(self.output, handleEvent: NSStreamEvent.hasSpaceAvailable)在线程3中调用它,或者原始线程是什么,以防止在输出阶段相互绊倒.

提前致谢!

注意:包含输入/输出处理的线程是使用NSThread.detachNewThreadSelector创建的

Answer 1

好吧,对于好奇的旁观者我,在对问题的评论的帮助下,我已经想出如何做我最初在问题中提出的问题(这最终是否会被重写以使用GCD是一个不同的问题)

解决方案(稍微增加代码的范围)是使用带有特定线程的performSelector.

final class ArbitraryConnection {

internal var streamThread: NSThread

let Session = NSURLSession.sharedSession()
let TheStack = [Structure]()
//This gets called asynchronously, e.g. in threads 3,4,5,6,7
func AddToStack(The Response) -> Void { 
   TheStack.insertAt(Structure(The Response), atIndex: 0))
   if output.hasSpaceAvailable == true {
      // This causes the stream event to be fired on multiple threads
      // This is what I want to call back into the original thread, e.g. in thread 2

      // Old way
      self.stream(self.output, handleEvent: NSStreamEvent.hasSpaceAvailable)
      // New way, that works
      if(streamThread != nil) {
          self.performSelector(Selector("startoutput"), onThread: streamThread!, withObject: nil, waitUntilDone: false)
      }
   }
}

func open -> Bool {
    // Some stuff
    streamThread = NSThread.currentThread()
}


final internal func startoutput -> Void {
   if(output.hasSpaceAvailable && outputIdle) {
        self.stream(self.output, handleEvent: NSStreamEvent.HasSpaceAvailable)
   }
}
// This is in the main loop, e.g. thread 2
func stream(aStream: NSStream, handleEvent: NSStreamEvent) {

   switch(NSStreamEvent) {

      case NSStreamEvent.OpenCompleted:
          // Do some open stuff
      case NSStreamEvent.HasBytesAvailable:
          Session.dataTaskWithRequest(requestFromInput, completionHandler: AddToStack)
      case NSStreamEvent.HasSpaceAvailable:
          // Do stuff with the output
      case NSStreamEvent.CloseCompleted:
          // Close the stuff
   }
}
}

因此,在具有选择器的对象上使用performSelector,并使用onThread告诉它要传递给哪个线程.我在执行选择器之前和执行调用之前检查两者以确保输出有可用空间(确保我不会绊倒自己)