iOS套接字写入服务器，服务器从客户端接收数据

Question

Im using this code to send image data (nsdata)to server

- (void)sendImageData: (UIImage *)image {
NSData *imageData = [UIImagePNGRepresentation(image) base64EncodedDataWithOptions:NSDataBase64Encoding64CharacterLineLength];
[outputStream write:[imageData bytes] maxLength:[imageData length]];

}

problem is: when I select a small size image, server will receive completely image's data Ive sent. However, when I send a lager image, server will not receive all my data. Why? Help me? Server receive data code:

int n = read(newSocket, buffer, 1024*256);
if (n < 0) {
    NSLog(@"error reading from socket!");
    return;
}
NSString *buffer2string = [NSString stringWithFormat:@"%s",buffer];
[stringData appendString:buffer2string];

Answer 1

I assume you are using TCP and in a block mode. TCP won't send all the data in one time, so you should call read method in a while loop. (read method returns when there are 1 byte in tcp's receive buffer by default) You must close the client connection to tell the server you have finished transmitting, or the server will never leave the while loop.

I didn't test the code, you can try it and tell me if it doesn't work.

int position = 0 ;
while (1) {
    int n = read(newSocket, buffer+position, 1024*256-position);
    if (n < 0) {
        NSLog(@"error reading from socket!");
        break ;
    } else if (n == 0) {
        NSLog(@"socket closed by peer") ;
        break ;
    } else {
        position += n ;
    }
}