I'm using iOS 5.1 I use this peace of code
[pathURL setResourceValue:[NSNumber numberWithBool:YES]
forKey:NSURLIsExcludedFromBackupKey
error:nil];
The folder where I put my content is (inside app sandbox) .../Library/Application Support/, not a /Documents folder
I do not receive any errors and the result of setResourceValue: is YES
Why do I see 2 MB is Settings -> iCloud -> ... etc. where I can check the apps data size?