site_archiver@lists.apple.com Delivered-To: cocoa-dev@lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:sender :to:subject:mime-version:content-type:content-transfer-encoding :content-disposition:x-google-sender-auth; bh=PST0EbiZIX3yPa7LkllBVnnemvaUV+3/+WNdMDNdSX8=; b=KtF7wiFheCz5BOAH9aRmv3WfEKhTZivGAlTHvVZtEvbzmkTSAQ4UdqXG1juMDg/5dv /P/Db7UNXh6xbyqz6ZOKaNXcyY3wiVkkqbh4CNQwI8X8vkQiwAty6ROj5nT39gNXnMoB u3nSNUs94NExFhWJ8jhxFqTfiFcj1WlWBsLBA= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:mime-version:content-type :content-transfer-encoding:content-disposition:x-google-sender-auth; b=tDEX4z9bVHMahvr3FwrQ2nYOW8esdrMnGxFO9K2mzqSk/jEPLT4c6PieXb9ZoecMZA IG+IozWbxLFGkNpzXT506f5iSS3BDDrc2rj/Sy12Zmysg9BycOmpbjk069wWLEtL3XkR fhbG+qNJwe8SzvSMCPkZ9ETcj6vArjzlCzkog= Heya I'm struggling a bit with NSViewControllers. My app displays a list of widgets. I have a Widget model, a WidgetView view (an NSView subclass), and a WidgetViewController (an NSViewController subclass). All of those have a one-to-one mapping - for any given WidgetViewController, it has a representedObject pointing to the Widget, and a view pointing to the WidgetView. The user can add/remove/reorder the widgets at any time. So, there's an array of Widgets, which the window controller observes, and whenever that array changes, it creates/deletes WidgetViewControllers (and inserts WidgetView subviews) to match. So far so good. (In fact, if I give the Widget model a strong relationship to the WidgetViewController (ie the Widget retains its view controller), it works perfectly. Unfortunately, that totally ignores the nice fluffy ideal of MVC separation.) There's a design flaw here somewhere, but I can't quite figure out what it is. It's highlighted by trying to reorder widgets. With KVC to-many relationships, there's no atomic way of moving an object from one position in an array to another : you remove the object, then re-insert it at the new location. But when the object is (temporarily) removed from the array, the window controller gets an observeValueForKeyPath saying it's been deleted, and so releases the corresponding WidgetViewController, the view gets deallocated, and so on. I'll then get a second observeValueForKeyPath saying that an object has been inserted, recreate the WidgetViewController, re-insert the view, etc etc. This seems pretty wrong to me. I can see a few workarounds (perhaps storing the kvo notifications until the end of the current runloop so I can add them together and figure out what was really a deletion and what was just a reordering), but they all seem pretty ugly and heavyweight. How is this usually handled? How do you managed your view controller lifetimes w.r.t. the model lifetime? Thanks for reading this far, any suggestions would be greatly appreciated -Jonathan _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/site_archiver%40lists.apple... This email sent to site_archiver@lists.apple.com