Hi I'm building an iPhoe app with a socket to a PC app , I need to get an image from this PC app. It's my first time using "CFStreamCreatePairWithSocketToHost".After I establish the socket with "NSOperation" I call

CFStreamClientContext streamContext = {0, self, NULL, NULL, NULL};
BOOL success = CFReadStreamSetClient(myReadStream, kMyNetworkEvents,MyStreamCallBack,&streamContext);
CFReadStreamScheduleWithRunLoop(myReadStream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);

then I call

CFWriteStreamWrite(myWriteStream, &writeBuffer, 3);
// Open read stream.
 if (!CFReadStreamOpen(myReadStream)) {
  // Notify error
 }
.
.
.
while(!cancelled && !finished) {
  SInt32 result = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.25, NO);


if (result == kCFRunLoopRunStopped || result == kCFRunLoopRunFinished) {
   break;
  }

if (([NSDate timeIntervalSinceReferenceDate] - _lastRead) > MyConnectionTimeout) {
   // Call timed out
   cancelled = YES;

break;
  }

// Also handle stream status 
  CFStreamStatus status = CFReadStreamGetStatus(myReadStream);
 }

and then when I get "kCFStreamEventHasBytesAvailable" I use

while (CFReadStreamHasBytesAvailable(myReadStream))
{
   CFReadStreamRead(myReadStream, readBuffer, 1000);
//and buffer the the bytes
}

It's unpredictable , sometimes I get the whole picture , sometime I got just part of it , and I can't understand what make the different. can someone has an idea what is wrong here? thanks