calling cancelAllOperations from nested NSOperations

I'm struggling with the following situation, pleaes bear with me as I've tried to be explain this as clearly as possible:

I have a class CoummintyOperation which is a subclass of a GroupOperation. CommuityOperation is called and added to an NSOperationQueue. CommunityOperation is in turn calling a whole bunch of NSOperations which are also sublcasses of GroupOperation and in turn are calling NSoperations within them. I've added dependencies for the GroupOperations in the CommunityOperation class. The issue I'm dealing with is if a nested operation fails I need to cancel ALL NSOperations in the CommunityOperations class, but I don't have access to the operationQueue that CommunityOperation was added to in order to call the cancelAllOperations method.

Can anyone help me out and explain how I can call this method, cancel All operations in this class (and therefore all nested Operations) and display an error message to the user.

Thanks in advance

Here's some sample code to help explain my issue: CommunityOperation gets put on an operationQueue from another class (not included)

public class CommunityOperation: GroupOperation {

    var updateOperation: UpdateOperation!
    var menuOperation: MenuOperation!
    var coreDataSaveOperation: CoreDataSaveOperation!

    var hasErrors = false

    public init() {

        super.init(operations: [])

        updateOperation = UpdateOperation()
        menuOperation = MenuOperation()
        coreDataSaveOperation = CoreDataSaveOperation()
        coreDataSaveOperation.addDependencies([updateOperation, menuOperation])

        self.addOperation(updateOperation)
        self.addOperation(menuOperation)
        self.addOperation(coreDataSaveOperation)
    }
}

MenuOperation class, which has nested Operations in it as well:

class UpdateMenuOperation: GroupOperation {

    let downloadGroupsOperation: DownloadGroupsOperation
    let downloadMembersOperation: DownloadMembersOperation

    init() {
            downloadGroupsOperation = DownloadGroupsOperation()
            downloadMembersOperation = DownloadMembersOperation(])

            super.init(operations: [downloadGroupsOperation,
                downloadMembersOperation
                ])
        }
}

DownloadGroupOperation class is again a subclass of GroupOperation. It has 2 operations - the first to download data and the second to parse the data:

class DownloadTopGroupsOperation: GroupOperation {
    let downloadOperation: DownloadOperation
    let importTopGroupsOperation: ImportOperation

    init() {
        downloadOperation = DownloadOperation()
        importOperation = ImportOperation()
        importOperation.addDependency(downloadOperation)
        importOperation.addCondition(NoCancelledDependencies())

        super.init(operations: [downloadOperation, importOperation])
    }
}

And finally (whew) the DownloadOperation class uses a NSURLSession and the method downloadTaskWithURL, it's in this method's completion handler that I want to call cancelAllOperations on the main operatioQueue if an error is returned:

class DownloadOperation: GroupOperation {
    init() {
        super.init(operations: [])
        if self.cancelled {
            return
       }
        let task = session.downloadTaskWithURL(url) { [weak self] url, response, error in
            self?.downloadFinished(url, response: response as? NSHTTPURLResponse, error: error)
        }
    }

    func downloadFinished(url: NSURL?, response: NSHTTPURLResponse?, error: NSError?) {

       if error {
         *cancel allOperations on queue*
       }
    }
}