Method for both removing and adding annotations

[virl]

Method for both removing and adding annotations in one go. Useful when integrating with CoreData.

[choefele]

Sorry for the late response and thanks for your pull request.

I was thinking to support this use case in a similar way to UITableView by surrounding add/remove calls with beginUpdates and endUpdates.

I think this would make for a cleaner API. What do you think?

[virl]

Yes, it will make more universal API, but for now I think it is overengineering. Let's accept my pull request and if someone will need begin/end updates then convert api to it.
Because when such updates are required, they are produced and accumulated on background thread in main application (as in my case) and begin/end updates will not simplify anything really.

[virl]

Hi. Will you accept this PR?

[mikrobi]

What's the status here?

[choefele]

I'm not really sure if the proposed API is a good idea. I was thinking about a beginUpdates/endUpdates style API.

@mikrobi In what context would this feature be useful to you?

[mikrobi]

Actually I agree with you. After taking a deeper look I'm just working with the currently available methods ;)

[ryancrunchi]

Hello,
thanks for your work. I need this feature because, as @virl, I'm using a map view with CoreData and NSFetchedResultsController as a datasource. I then use NSFetchedResultsControllerDelegate methods to update my map. So, for each updated objects in my fetchedResultsController I need to remove its annotation and re-add it in order to get it state refreshed. When I call both removeAnnotations:withCompletionHandler: and addAnnotations:withCompletionHandler: just after, I have duplicated annotations on map.

[markkrenek]

A beginUpdates/endUpdates style API would be great. But here's how I solved this for my NSFetchedResultsController case using the current code base:

Instead of performing add/removeAnnotations for each update, just collection those annotations in a couple of arrays and them batch process them in controllerDidChangeContent.

private var homesAddedByFRC: [Home]?
private var homesRemovedByFRC: [Home]?

func fetchedResultsControllerWillChangeContent(controller: FetchedResultsController<Home>)
{
    // Handle adds and removes as a large batch.
    homesAddedByFRC = []
    homesRemovedByFRC = []
}

func fetchedResultsController(controller: FetchedResultsController<Home>, didChangeObject change: FetchedResultsObjectChange<Home>)
{
    switch change
    {
        case let .Insert(home, _):
            homesAddedByFRC.append(home)

        case let .Delete(home, _):
            homesRemovedByFRC.append(home)

        case let .Move(home, _, _):
            homesRemovedByFRC.append(home)
            homesAddedByFRC.append(home)

        case let .Update(home, _):
            homesRemovedByFRC.append(home)
            homesAddedByFRC.append(home)
    }
}

fetchedResultsControllerDidChangeContent(controller: FetchedResultsController<Home>)
{
    // Handle removed homes first because in some instances, we removed and then added the same home in order to get it updated.
    self.removeAnnotationsForHomes(homesRemovedByFRC!)
    self.addAnnotationsForHomes(homesAddedByFRC!)

    homesAddedByFRC = nil
    homesRemovedByFRC = nil
}

This code snippet is not a direct copy/paste from my code, so it may not be 100% syntactically correct.

[choefele]

@markkrenek Thanks for your example