如何从外部附件异步发送和接收数据

Question

我对从外部附件异步方式发送和接收数据感到困惑。我使用MFi External Accessory，我检查了EADemo，但似乎发送和接收数据同步方式。对此有任何建议，在此先感谢。

Answer 1

首先，您必须将输入/输出流附加到 runLoop：

[[session inputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[[session inputStream] open];
[[session outputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[[session outputStream] open];

成为他们的代表：

[[session outputStream] setDelegate:self];
[[session inputStream] setDelegate:self];

一旦你成为委托，你必须实现这个方法：

-(void)stream:handleEvent:{};

这是一个例子：

-(void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)_event {
    switch (_event)
    {
        case NSStreamEventHasBytesAvailable:
            /* This part will be executed every time your rx buffer contains at least 1 byte */
            switch(state) {
                uint8_t ch;
                /* Read byte per byte */
                [stream read:&ch maxLength:1];
                /* now ch contains a byte from your MFI device
                ** and 'read' function decrease the length of the rx buffer by -1 */
            }
            break;
    }
}

这是将数据写入流的命令：

/* txQueue is a NSData containing data to transmit. */
[[session outputStream] write:(uint8_t *)[txQueue bytes] maxLength:[txQueue length]];