Question

I have NSOutlineView with rows of variable (in runtime) height. It’s simple to change the height immediately with outlineView: heightOfRowByItem: method in delegate. But I want to animate row height like during expanding/collapsing animation.

How to do this?

Answer 1

On your NSOutlineView call noteHeightOfRowsWithIndexesChanged: like:

// index set with all rows that did change height
NSIndexSet *rows = [NSIndexSet indexSetWithIndex:1];
[self.outlineView noteHeightOfRowsWithIndexesChanged:rows];

This will animate the rows to the new height as returned by the outlineView:heightOfRowByItem: delegate method.

From the documentation:

For View-based tables, this method will animate.
[…]
For cell based tables, this method normally doesn’t animate. However, it will animate if you call it inside a beginUpdates/endUpdates block.