外部附件流在100％的时间内无法正常工作

Question

输入和输出流始终打开，并使用正确的NSStreamEvent代码（NSStreamEventOpenCompleted）调用相应的委托方法。但是，在某些openSession尝试中，流成功打开，但它们不起作用。有时我只能写入输出流，但我无法从输入流中读取数据。有时我无法读写。

有没有人遇到这个问题或有任何想法，为什么发生这种情况？任何帮助表示赞赏。谢谢。

下面是一些相关的代码

- (BOOL)openSession 
{ 
    _session = [[EASession alloc] initWithAccessory:_selectedAccessory 
             forProtocol:_protocolString]; 

    if (!_session) 
     return false; 

    [_selectedAccessory setDelegate:self]; 
    [[_session inputStream] setDelegate:self]; 
    [[_session outputStream] setDelegate:self]; 

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),^{ 

     [[_session inputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] 
              forMode:NSDefaultRunLoopMode]; 
     [[_session inputStream] open]; 

     [[_session outputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] 
              forMode:NSDefaultRunLoopMode]; 
     [[_session outputStream] open]; 

     [[NSRunLoop currentRunLoop] run]; 
    }); 

    return true; 
} 

- (void)setupControllerForAccessory:(EAAccessory *)accessory withProtocolString:(NSString *)protocolString 
{ 
    _selectedAccessory = accessory; 
    _protocolString = [protocolString copy]; 
} 

/** 
* There is something weird happening here too, this always get called twice when an accessory 
* gets connected. Once without a protocol string and once with a protocol string. I just 
* ignore the one without a protocol string. 
*/ 
- (void)accessoryConnected:(NSNotification *)notification 
{ 
    EAAccessory *connectedEA = [notification.userInfo objectForKey:@"EAAccessoryKey"]; 

    // Check to see if the connected EA has a protocol string 
    if ([[connectedEA protocolStrings] count] == 0) 
     return; 

    [self setupControllerForAccessory:connectedEA 
        withProtocolString:[[connectedEA protocolStrings] objectAtIndex:0]]; 
    [self openSession]; 
} 

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode 
{ 
    switch (eventCode) { 
     case NSStreamEventOpenCompleted: 
      // This case always gets called twice, once for input and once for output 
      NSLog(@"stream %@ opened", aStream); 
      break; 
     case NSStreamEventHasBytesAvailable: 
      break; 
     case NSStreamEventHasSpaceAvailable: 
      break; 
     case NSStreamEventErrorOccurred: 
      break; 
     case NSStreamEventEndEncountered: 
      [self closeSession]; 
      break; 
     default: 
      break; 
    } 
} 

- (void)closeSession 
{ 
    [[_session inputStream] close]; 
    [[_session inputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 
    [[_session inputStream] setDelegate:nil]; 

    [[_session outputStream] close]; 
    [[_session outputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 
    [[_session outputStream] setDelegate:nil]; 

    _session = nil; 
    _selectedAccessory = nil; 
    _protocolString = nil; 
} 

Answer 1

我不能添加到您的问题评论（少点！），但我有一些暗示，因为我的团队也面临着这是间歇使用流的同样的问题。 我们向网络团队提出了同样的错误。如果可能，请尝试记录错误，很可能在调试器控制台中出现错误“Stream was unexpected”。这可能会出现，也可能不会出现。

以下是苹果文档中提供的类似代码，它也有相同的问题。 https://developer.apple.com/library/ios/samplecode/SimpleURLConnections/Listings/PostController_m.html#//apple_ref/doc/uid/DTS40009245-PostController_m-DontLinkElementID_12