我想通过套接字将UI
Image发送到服务器.
a)我打开输出流:
- (IBAction)send:(id)sender { NSURL *website = [NSURL URLWithString:str_IP]; NSHost *host = [NSHost hostWithName:[website host]]; [Nsstream getStreamsToHost:host port:1100 inputStream:nil outputStream:&oStream]; [oStream retain]; [oStream setDelegate:self]; [oStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; [oStream open]; }
b)在打开完成后我将NSData写入outputstream并在发生错误时处理错误.
- (void) stream: (Nsstream *) stream handleEvent: (NsstreamEvent) eventCode { //printf("EVENT: Start.\n"); switch(eventCode) { case NsstreamEventOpenCompleted: { //printf("EVENT: Open completed.\n"); if(stream == oStream) { //printf("Sending...\n"); NSData *data = UIImageJPEGRepresentation(drawImage.image,90); NSInteger x = [oStream write:[data bytes] maxLength:[data length]]; } break; } case NsstreamEventEndEncountered: { //printf("EVENT: End encountered.\n"); break; } case NsstreamEventHasspaceAvailable: { //printf("EVENT: Has space available.\n"); break; } case NsstreamEventHasBytesAvailable: { //printf("EVENT: Has bytes available.\n"); break; } case NsstreamEventErrorOccurred: { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error Occurred" message:nil delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; [alert show]; [alert release]; break; } case NsstreamEventNone: { //printf("EVENT: None.\n"); break; } } //printf("EVENT: End.\n"); }
当我运行此代码时,将调用NsstreamEventOpenCompleted和NsstreamEventErrorOccurred.成功调用NSOutputStream的write方法,并且所有数据都不是nil.但是在将数据写入oStream之后,eventCode将更改为NsstreamEventErrorOccurred.
所以我想也许这不是使用[oStream write]的正确方法.那么使用此消息的正确方法是什么?我发现这条消息返回一个-1073748088的NSInteger,可能是什么问题?
解决方法
只有在输出流中有空间可用后才应该写入数据.当流完成打开时,它并不总是立即有可用空间,因此写入它将不起作用.如果将write调用移动到NsstreamEventHasspaceAvailable处理程序,它应该会成功.
此外,套接字另一端的计算机无法知道您发送的数据的长度.除非您通过关闭套接字发出数据结束信号,否则应该明确地将数据长度与数据一起发送:
case NsstreamEventHasspaceAvailable: { if(stream == oStream) { NSData *data = UIImageJPEGRepresentation(drawImage.image,90); // Convert from host to network endianness uint32_t length = (uint32_t)htonl([data length]); // Don't forget to check the return value of 'write' [oStream write:(uint8_t *)&length maxLength:4]; [oStream write:[data bytes] maxLength:length]; } break; }
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