Write file to etc directory in mac os x

I am trying to write file into /etc folder on Mac OS X.

[[textView string] writeToFile:@"/etc/info.txt" atomically:YES encoding:NSUnicodeStringEncoding error:&error];

It throws error that I don't have permission to write there ( naturally ), but I don't understand how to get permission to be able to write into the System folders.

Also can somebody provide simple example?

Please help. Thank you.

Okay, after researching quite a bit I believe I found a more/less simple method. First check out the link: Cocoa - Gaining Root Access for NSFileManager

They suggest using already made class "BLAuthentication" - which takes care of lots of authentication coding for you. Google it to download, add to the project and use in your code. Here is a example of how simple that is:

id blTmp = [BLAuthentication sharedInstance];

NSString *myCommand = [[NSString alloc] initWithString:@"/bin/cp"];

NSArray *para = [[NSArray alloc] initWithObjects:fileName, @"/etc/", nil];

[blTmp authenticate:myCommand];

if([blTmp isAuthenticated:myCommand] == true) {
    NSLog(@"Authenticated");
    [blTmp executeCommandSynced:myCommand withArgs:para];

} else { NSLog(@"Not Authenticated"); }

[fileName release];
[myCommand release];
[para release];

Naturally above approach doesn't exactly answers my own question, since with above example you don't directly write to "/etc". Instead first I have to write file to "/tmp" (or other directory of your choice) and then using "cp" command in unix, copy it over to "/etc" (using "BLAuthentication" for authentication).

This is the simplest to do it, that I managed to find.

*Note: This method might not work in Lion (Mac os 10.7) since "BLAuthentication" uses deprecated function "AuthorizationExecuteWithPrivileges". Also I would suggest watching WWDC 2011 where they talk about security and proper ways of accomplishing the task. However if you need to prototype and/or play around, "BLAuthentication" should do the trick.