Have a reloadData for a UITableView animate when changing

Question

I have a UITableView that has two modes. When we switch between the modes I have a different number of sections and cells per section. Ideally, it would do some cool anima

Answer 1

I believe you can just update your data structure, then:

[tableView beginUpdates];
[tableView deleteSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:YES];
[tableView insertSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:YES];
[tableView endUpdates];

Also, the "withRowAnimation" is not exactly a boolean, but an animation style:

UITableViewRowAnimationFade,
UITableViewRowAnimationRight,
UITableViewRowAnimationLeft,
UITableViewRowAnimationTop,
UITableViewRowAnimationBottom,
UITableViewRowAnimationNone,
UITableViewRowAnimationMiddle

Answer 2

Swift Implementation:

let range = NSMakeRange(0, self.tableView!.numberOfSections())
let indexSet = NSIndexSet(indexesInRange: range)
self.tableView!.reloadSections(indexSet, withRowAnimation: UITableViewRowAnimation.Automatic)

Answer 3

UITableView has a field called 'indexPathsForVisibleRows' that you can use to animate the visible rows using the 'reloadItemsAtIndexPaths' method.

    guard let indexPaths = tableView.indexPathsForVisibleRows
    else { return }
    
    self.tableView.layoutIfNeeded()
    self.tableView.reloadItemsAtIndexPaths(indexPaths, animationStyle: .automatic)

Answer 4

Native UITableView animations in Swift

Insert and delete rows all at once with tableView.performBatchUpdates so they occur simultaneously. Building on the answer from @iKenndac use methods such as:

• tableView.insertSections
• tableView.insertRows
• tableView.deleteSections
• tableView.deleteRows

Ex:

 tableView.performBatchUpdates({
   tableView.insertSections([0], with: .top)
 })

This inserts a section at the zero position with an animation that loads from the top. This will re-run the cellForRowAt method and check for a new cell at that position. You could reload the entire table view this way with specific animations.

Re: the OP question, a conditional flag would have been needed to show the cells for the alternate table view state.

Answer 5

The way to approach this is to tell the tableView to remove and add rows and sections with the

insertRowsAtIndexPaths:withRowAnimation:,
deleteRowsAtIndexPaths:withRowAnimation:,
insertSections:withRowAnimation: and
deleteSections:withRowAnimation:

methods of UITableView.

When you call these methods, the table will animate in/out the items you requested, then call reloadData on itself so you can update the state after this animation. This part is important - if you animate away everything but don't change the data returned by the table's dataSource, the rows will appear again after the animation completes.

So, your application flow would be:

[self setTableIsInSecondState:YES];

[myTable deleteSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:YES]];

As long as your table's dataSource methods return the correct new set of sections and rows by checking [self tableIsInSecondState] (or whatever), this will achieve the effect you're looking for.