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?
Finally I found the solution by myself The clue is to apply NSURLIsExcludedFromBackupKey to root folder not to every file you want to exclude from backup
so at very beginning you should call this with (for example) "Library/Application Support" folder
It's worth to note that you can't just set the flag on NSHomeDirectory(). It has to be internal to that path.
来源:https://stackoverflow.com/questions/12093774/excluding-files-from-icloud-backup