Re: -outlineView:heightOfRowByItem: gets an item of NULL??

FROM : Mike Abdullah
DATE : Thu Feb 21 21:04:56 2008

Although the docs don't mention it for this method, quite often an 
item of nil is used to represent the tree's root object. I would 
suggest therefore returning the default height of a table cell.

Mike.

On 21 Feb 2008, at 19:32, John Stiles wrote:

> My outline view can occasionally get multi-line entries, so I've 
> implemented -outlineView:heightOfRowByItem: in the delegate. 
> Normally this works like a charm.
>
> Now I'm working on some code to support dragging and dropping items 
> between one outline view and another outline view.  (For what it's 
> worth, none of the items in this particular outline view are using a 
> nonstandard height in this case.) Suddenly, I've found that if I 
> start dragging items back and forth, after about ten tries or so, -
> outlineView:heightOfRowByItem: is called with an item of "nil"!! I 
> haven't narrowed down a distinct pattern yet.
>
> This causes an assertion to fire in my code because the first thing 
> I do is assert that [item isKindOfClass:[MyItem class]]. This 
> assertion hasn't ever gone off before.
>
> Is it expected that this delegate method could occasionally be 
> called with a nil item?
>
> As a workaround, should I just return [outlineView rowHeight] if I 
> get nil?
>
>
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