Unable to write data into NSOutputStream

Question

I am trying to send large sized images from the server to client using the write method of the NSOuptutStream. However I find that after writing 684032 bytes, no more bytes are getting written by the stream. I find this particularly strange. I am able to send images of size < 680432 and receive them properly at the client side. Attached code snippet below. It would be great if someone can point out where exactly I am going wrong.

UIImage *img;
img = [UIImage imageWithContentsOfFile:path];
NSMutableData *imgData = [UIImageJPEGRepresentation(img, 1.0) mutableCopy];

const void *bytes = [imgData mutableBytes];
NSInteger length = [imgData length];
self.bufferLimit = length;
NSLog(@"self.bufferoffset %d self.bufferlimit %d", self.bufferOffset, self.bufferLimit);

uint8_t *crypto_data = (uint8_t *)bytes;                   
NSInteger   bytesWritten;

if([self.outputStream hasSpaceAvailable]) {
    NSLog(@"Space Available");
} else NSLog(@"Space Not Available");

while (self.bufferOffset < self.bufferLimit) {

    bytesWritten = [self.outputStream write:(uint8_t *)crypto_data maxLength:1024];
    NSLog(@"server: bytes weritten %d",bytesWritten);
    assert(bytesWritten != 0);
    if (bytesWritten == -1) {
        [self stopSendWithStatus:@"output buffer write error"];
    } else {
        self.bufferOffset += bytesWritten;
    }
    NSLog(@"self.bufferoffset %d self.bufferlimit %d", self.bufferOffset, self.bufferLimit);
} 
NSLog(@"Done sending");
[self.outputStream close]; 

When my code hangs this is the output I am left with

...
2012-07-04 13:53:20.903 BasicClientServer[1707:f803] self.bufferoffset 681984 self.bufferlimit 1334301
2012-07-04 13:53:20.903 BasicClientServer[1707:f803] server: bytes weritten 1024
2012-07-04 13:53:20.904 BasicClientServer[1707:f803] self.bufferoffset 683008 self.bufferlimit 1334301
2012-07-04 13:53:20.905 BasicClientServer[1707:f803] server: bytes weritten 1024
2012-07-04 13:53:20.906 BasicClientServer[1707:f803] self.bufferoffset 684032 self.bufferlimit 1334301

and doesnt go beyond this point