Download and save video from web in iphone development

Question

Hi,

I am trying this code to write m4v file. This code works fine if i am writing any txt file. But it's not work for m4v. It creates 4kb blank m4v file for me. Can someone tell wht's going wrong in this code.

- (void)viewDidLoad {

    NSString *post=@"key1=val1&key2=val2";
    NSData *postData= [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:@"http://192.168.1.100:85/km/nano01_4_3.m4v"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];

    NSURLConnection *conn=[[NSURLConnection alloc] initWithRequest:request delegate:self];

    if (conn)
    {
        receivedData = [[NSMutableData data] retain];
        //[postData writeToFile:@"/Users/sachinuttam/desktop/php.txt" atomically:YES];
        NSString *msg = [[NSString alloc] initWithFormat:@"image location 0%i",1];
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"touch image value" message:msg delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
        [msg release];
        [alert show];
        [alert release];
    } else
    { // inform the user that the download could not be made
        NSString *msg = [[NSString alloc] initWithFormat:@"image location 0%i",123];
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"touch image value" message:msg delegate:self cancelButtonTitle:@"Ok!" otherButtonTitles:nil];
        [msg release];
        [alert show];
        [alert release];
    }

    [super viewDidLoad];
}

/*- (void)didReceiveMemoryWarning
 {
 [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview.
 // Release anything that's not essential, such as cached data.
 } */

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [receivedData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // do something with the data
    // receivedData is declared as a method instance elsewhere
    NSLog(@"Succeeded! Received %d bytes of data",[receivedData length]);
    NSString *aStr = [[NSString alloc] initWithData:receivedData encoding:NSASCIIStringEncoding];
    NSLog(aStr);

    [receivedData writeToFile:@"/Users/sachinuttam/desktop/nano01_4_3.m4v" atomically:YES];

    //[[NSData dataWithContentsOfURL:myURL] writeToFile:[cachesDirectory stringByAppendingString:@"/test.mp4"] atomically:NO];
    // release the connection, and the data object
    [receivedData release];
}