UDP通讯，收到数据做出反应遇到麻烦

• (BOOL)onUdpSocket:(AsyncUdpSocket *)sock

   didReceiveData:(NSData *)data
          withTag:(long)tag
         fromHost:(NSString *)host
             port:(UInt16)port{
  NSLog(@"received data");
  

char *d = [data bytes];
if(d[0] == 0x55fc)
{
    [_zanting setBackgroundImage:[UIImage imageNamed:@"Pause.png"] forState:UIControlStateNormal];
}
else if(d[0] == 0x66fc)
{
    [_zanting setBackgroundImage:[UIImage imageNamed:@"Play.png"] forState:UIControlStateNormal];
}

[udpSocket receiveWithTimeout:-1 tag:0];
return YES;

}

上面这个代码是收到2个不同的16进制数据 变换2张不同的图片，但是有问题！ 请高手帮我分析下