Re: -outlineView:heightOfRowByItem: gets an item of NULL??
Re: -outlineView:heightOfRowByItem: gets an item of NULL??
- Subject: Re: -outlineView:heightOfRowByItem: gets an item of NULL??
- From: John Stiles <email@hidden>
- Date: Fri, 22 Feb 2008 11:53:06 -0800
Is it illegal to call -reloadData from inside a delegate method?
Because, yeah, when -outlineView:acceptDrop:item:childIndex: is called,
that could easily lead to the whole contents of the outline view getting
rebuilt from scratch. And this could definitely lead to calls to
-reloadData or -reloadItem:reloadChildren:.
If this is going to bite me down the line, what are my options? Sadly,
it's not possible to defer method calls until after
-outlineView:acceptDrop:item:childIndex: returns, due to an AppKit bug:
rdar://5686701 Drag-and-drop from an outline view runs a
run-loop in NSDefaultRunLoopMode
So I don't really know how to work around this bug without going to
extreme lengths.
Please go into a little more detail about what a delegate method can or
cannot do. Right now it's entirely possible, in some corner cases, that
small things like selection-change events (e.g.
-outlineViewSelectionDidChange:) could lead to huge ripple effects which
end up causing the whole window to rebuild itself from scratch. If
that's not kosher, I need to seriously reevaluate a lot of code.
Corbin Dunn wrote:
> It shouldn't ask you for the height of a NULL item.
>
> This is either:
> 1. a bug in nsoutlineview
> 2. your code may be reloading the nsoutlineview in one of the
delegate methods, putting it into a "strange" state. If you see this
happening consistently, you may want to break on NSOutlineView
reloadData and see if it is getting called when it shouldn't be.
>
> corbin
>
> On Feb 21, 2008, at 12:06 PM, John Stiles wrote:
>
>> Fair enough, but the root item is never represented graphically in a
table, so there wouldn't be a need to ask for its row height…?
>> Anyway, I filed a radar… we'll see what happens.
>>
>>
>> Mike Abdullah wrote:
>>> 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.
>>>
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