流來獲取數據 - NSInputStream

Question

全部，

我有一個服務器有一個tcp套接字流進行通信。我需要訪問該流並閱讀它需要發送給我的初始數據。

我現在的代碼如下。說實話，我完全失明。我不確定這是否正確，更不用說這項工作是正確的。

-(void) initNetworkCommunication 
{ 
    //input stream 
    NSInputStream *iStream; 
    NSURL *url = [url initWithString:@"192.168.17.1:2004"]; 

    [iStream initWithURL:url]; 
    [iStream setDelegate:self]; 
    [iStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 
    [iStream open]; 

} 

因此，從我看到它的方式，此代碼初始化流，但我如何從流中讀取？

感謝

Answer 1

有兩種方式來獲得從流數據：輪詢和使用流事件。

輪詢更簡單，但會阻塞其運行的線程。如果使用此方法，則不需要執行setDelegate:或scheduleInRunLoop:forMode:調用。輪詢通過反覆調用read:maxLength:來執行。

NSInteger result; 
uint8_t buffer[BUFFER_LEN]; // BUFFER_LEN can be any positive integer 
while((result = [iStream read:buffer maxLength:BUFFER_LEN]) != 0) { 
    if(result > 0) { 
     // buffer contains result bytes of data to be handled 
    } else { 
     // The stream had an error. You can get an NSError object using [iStream streamError] 
    } 
} 
// Either the stream ran out of data or there was an error 

使用流事件需要設置委託並將流添加到運行循環。當發生某些事件時（包括接收數據時），流將不會阻塞線程，而會向其代理髮送stream:handleEvent:消息。代表可以從流中檢索數據。下面是一個例子stream:handleEvent:方法：

- (void)stream:(NSInputStream *)iStream handleEvent:(NSStreamEvent)event { 
    BOOL shouldClose = NO; 
    switch(event) { 
     case NSStreamEventEndEncountered: 
      shouldClose = YES; 
      // If all data hasn't been read, fall through to the "has bytes" event 
      if(![iStream hasBytesAvailable]) break; 
     case NSStreamEventHasBytesAvailable: ; // We need a semicolon here before we can declare local variables 
      uint8_t *buffer; 
      NSUInteger length; 
      BOOL freeBuffer = NO; 
      // The stream has data. Try to get its internal buffer instead of creating one 
      if(![iStream getBuffer:&buffer length:&length]) { 
       // The stream couldn't provide its internal buffer. We have to make one ourselves 
       buffer = malloc(BUFFER_LEN * sizeof(uint8_t)); 
       freeBuffer = YES; 
       NSInteger result = [iStream read:buffer maxLength:BUFFER_LEN]; 
       if(result < 0) { 
        // error copying to buffer 
        break; 
       } 
       length = result; 
      } 
      // length bytes of data in buffer 
      if(freeBuffer) free(buffer); 
      break; 
     case NSStreamEventErrorOccurred: 
      // some other error 
      shouldClose = YES; 
      break; 
    } 
    if(shouldClose) [iStream close]; 
}