On Jul 10, 2014, at 4:57 PM, Ken Thomases <k...@codeweavers.com> wrote:
> Are the items that result from unarchiving the persistent object the same > items as your data source returns via -outlineView:child:ofItem:? I believe > they have to be the same by pointer identity, not just equal as by -isEqual:. They are content-equal, but they can't be pointer-identical because I archive them to NSData objects and unarchive them using NSKeyedArchiver and NSKeyedUnarchiver. The reference document comes as close as possible to saying that we're supposed to use NSKeyedArchiver and NSKeyedUnarchiver without quite actually saying so. For example, according to the NSOutlineViewDataSource reference for -outlineView:persistentObjectForItem:, the return value should be "An archived representation of item." If this means we should use NSKeyedArchiver, which I assume it does, then pointer-identity couldn't be a requirement, could it? There is nothing in the reference document to suggest that pointer-identity is required, for what that's worth. My items are standard NSDictionary objects, and I have confirmed that they are properly reconstituted in -outlineView:itemForPersistentObject. > Rather than archiving the item itself, you should perhaps archive uniquely > identifying attributes of the item so that you can find the corresponding > item among the new model and return that. Online discussions of this problem in the past have suggested that archiving unique strings works, and discussions in the Core Data context have suggested that using UUIDs works. But the reference document makes no suggestion that this is required. In fact, just after the quotation above, it goes on to say "If the item is an archived object, this method may return the item." Having to implement UUIDs in my data source for the sole purpose of implementing expand/collapse state survival across application relaunches seems a bit much. I did try calling -outlineView:itemForPersistentObject: myself in -awakeFromNib, matching the unarchived items to their counterparts in the datasource and loading the object from the datasource, and it didn't work. However, that was late in the day yesterday and I may not have gotten it quite right. I'll try again this morning. But this seems counter-intuitive, because I have confirmed that AppKit calls -outlineView:itemForPersistentObject: itself at launch, once for each archived item in user defaults. The documentation does not suggest in any way that I should call it myself, which would be counter to the normal behavior of datasource methods. -- Bill Cheeseman - b...@cheeseman.name _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
