UITableView row animation duration and completion

Question

Is there a way to either specify the duration for UITableView row animations, or to get a callback when the animation completes?

What I would like to do is flash the scroll indicators after the animation completes. Doing the flash before then doesn't do anything. So far the workaround I have is to delay half a second (that seems to be the default animation duration), i.e.:

[self.tableView insertRowsAtIndexPaths:newRows
                      withRowAnimation:UITableViewRowAnimationFade];
[self.tableView performSelector:@selector(flashScrollIndicators)
                     withObject:nil
                     afterDelay:0.5];

Answer 1

That's one hell of a useful trick! I wrote a UITableView extension to avoid writing CATransaction stuff all the time.

import UIKit

extension UITableView {

    /// Perform a series of method calls that insert, delete, or select rows and sections of the table view.
    /// This is equivalent to a beginUpdates() / endUpdates() sequence, 
    /// with a completion closure when the animation is finished.
    /// Parameter update: the update operation to perform on the tableView.
    /// Parameter completion: the completion closure to be executed when the animation is completed.

    func performUpdate(_ update: ()->Void, completion: (()->Void)?) {

        CATransaction.begin()
        CATransaction.setCompletionBlock(completion)

        // Table View update on row / section
        beginUpdates()
        update()
        endUpdates()

        CATransaction.commit()
    }

}

This is used like so:

// Insert in the tableView the section we just added in sections
self.tableView.performUpdate({
            self.tableView.insertSections([newSectionIndex], with: UITableViewRowAnimation.top)

        }, completion: {
            // Scroll to next section
            let nextSectionIndexPath = IndexPath(row: 0, section: newSectionIndex)
            self.tableView.scrollToRow(at: nextSectionIndexPath, at: .top, animated: true)
        })

Answer 2

For me I needed this for a collectionView. I've made a simple extension to solve this:

extension UICollectionView {

    func reloadSections(sections: NSIndexSet, completion: () -> Void){
        CATransaction.begin()
        CATransaction.setCompletionBlock(completion)

        self.reloadSections(sections)

        CATransaction.commit()
    }

}