UITableView row animation duration and completion callback

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开发者_运维百科 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];

Just came across this. Here's how to do it:

Objective-C

[CATransaction begin];
[tableView beginUpdates];
[CATransaction setCompletionBlock: ^{
    // Code to be executed upon completion
}];
[tableView insertRowsAtIndexPaths: indexPaths
                 withRowAnimation: UITableViewRowAnimationAutomatic];
[tableView endUpdates];
[CATransaction commit];

Swift

CATransaction.begin()
tableView.beginUpdates()
CATransaction.setCompletionBlock {
    // Code to be executed upon completion
}
tableView.insertRowsAtIndexPaths(indexArray, withRowAnimation: .Top)
tableView.endUpdates()
CATransaction.commit()

Expanding on karwag's fine answer, note that on iOS 7, surrounding the CATransaction with a UIView Animation offers control of the table animation duration.

[UIView beginAnimations:@"myAnimationId" context:nil];

[UIView setAnimationDuration:10.0]; // Set duration here

[CATransaction begin];
[CATransaction setCompletionBlock:^{
    NSLog(@"Complete!");
}];

[myTable beginUpdates];
// my table changes
[myTable endUpdates];

[CATransaction commit];
[UIView commitAnimations];

The UIView animation's duration has no effect on iOS 6. Perhaps iOS 7 table animations are implemented differently, at the UIView level.

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)
})

Shortening Brent's fine answer, for at least iOS 7 you can wrap this all tersely in a [UIView animateWithDuration:delay:options:animations:completion:] call:

[UIView animateWithDuration:10 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
  [self.tableView beginUpdates];
  [self.tableView endUpdates];
} completion:^(BOOL finished) {
  // completion code
}];

though, I can't seem to override the default animation curve from anything other than EaseInOut.

Here's a Swift version of karwag's answer

CATransaction.begin()
tableView.beginUpdates()
CATransaction.setCompletionBlock { () -> Void in
    // your code here
}
tableView.insertRowsAtIndexPaths(indexArray, withRowAnimation: .Top)
tableView.endUpdates()
CATransaction.commit()

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()
    }

}

Nowadays if you want to do this there is new function starting from iOS 11:

- (void)performBatchUpdates:(void (^)(void))updates 
                 completion:(void (^)(BOOL finished))completion;

In updates closures you place the same code as in beginUpdates()/endUpdates section. And the completion is executed after all animations.

As tableView's performBatch method is available starting from iOS 11 only, you can use following extension:

extension UITableView {
func performUpdates(_ updates: @escaping () -> Void, completion: @escaping (Bool) -> Void) {
        if #available(iOS 11.0, *) {
            self.performBatchUpdates({
                updates()
            }, completion: completion)
        } else {
            CATransaction.begin()
            beginUpdates()
            CATransaction.setCompletionBlock {
                completion(true)
            }
            updates()
            endUpdates()
            CATransaction.commit()
        }
    }
}

Antoine's answer is pretty good – but is for UICollectionView. Here it is for UITableView:

extension UITableView {
    func reloadSections(_ sections: IndexSet, with rowAnimation: RowAnimation, completion: (() -> Void)?) {
        CATransaction.begin()
        CATransaction.setCompletionBlock(completion)
        
        self.reloadSections(sections, with: rowAnimation)
        
        CATransaction.commit()
    }
}

Called like so:

tableView.reloadSections(IndexSet(0), with: .none, completion: {
    // Do the end of animation thing        
})

If someone is facing the problem when tableView is ignoring animation parameters from UIView.animate and using "from up to down" default animation for reloading rows, I've found a strange solution:

You need to:

1. Silence tableView animation
2. Use transitionAnimation instead

Example:

let indicesToUpdate = [IndexPath(row: 1, section: 0)]
UIView.transition(with: self.tableView,
                      duration: 0.5,
                      options: [.transitionCrossDissolve,
                                .allowUserInteraction,
                                .beginFromCurrentState],
                      animations: {
                        UIView.performWithoutAnimation {
                            self.tableView.reloadRows(at: indicesToUpdate,
                                                      with: .none)
                        }
                      })

PS: UIView.transition(..) also has optional completion :)

You could try to wrap the insertRowsAtIndexPath in a

- (void)beginUpdates
- (void)endUpdates

transaction, then do the flash afterwards.