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;
}
