Prevent app from backing up documents folder?

Question

I\'m trying to prevent my app backing up files to iCloud but have become completely confused and a little lost.

-EDIT-

I\'ve updated this to reflect the chan

Answer 1

- (BOOL)addSkipBackupAttributeToItemAtURL:(NSURL *)URL
{

    assert([[NSFileManager defaultManager] fileExistsAtPath: [URL path]]);

    NSError *error = nil;
    BOOL success = [URL setResourceValue: [NSNumber numberWithBool: YES]
                                  forKey: NSURLIsExcludedFromBackupKey error: &error];
    if(!success){
        NSLog(@"Error excluding %@ from backup %@", [URL lastPathComponent], error);
    }
    return success;
}

NSURL *documentURLWithExtension = [documentURL URLByAppendingPathExtension:extensionType];

pass this "documentURLWithExtension" to this function

[self addSkipBackupAttributeToItemAtURL:documentURLWithExtension];

Answer 2

In Swift:

//Path of document directory
var docPathAry : NSArray! = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
var docDirPathStr: AnyObject? = docPathAry.count > 0 ? docPathAry[0] : nil

self.addSkipBackupAttributeToItemAtURL(NSURL.fileURLWithPath(docDirPathStr as NSString))

and:

func addSkipBackupAttributeToItemAtURL(URL: NSURL!) -> Bool {
    assert(NSFileManager.defaultManager().fileExistsAtPath(URL.path))
    var err : NSError? = nil
    var success : Bool! = URL.setResourceValue(NSNumber.numberWithBool(true), forKey: NSURLIsExcludedFromBackupKey, error: &err)

    if(!success) {
        println("Error excluding \(URL.lastPathComponent) from backup\(err) ")
    }

    return success
}