On 5 Jan 2010, at 17:34, Martin Stanley wrote: > Thanks for the very quick response! > > I don't quite understand step 2: how do I decide what to return from > -openDocumentWithContentsOfURL: if the callback hasn't been called yet and > therefore I don't know if the user cancelled the close of the first document?
I mean to say that either approach should work. But I haven't tried them, so keep your options open. > > I think the basic problem for me is that -canCloseDocument… does not block. Well it can't block, because the sheet needs to be interacted with. > > Martin > > > On 2010-01-05, at 12:10 PM, Mike Abdullah wrote: > >> Override -openDocumentWithContentsOfURL: >> >> 1. If you've already got a document open, send -canCloseDocument… to the >> open document, supplying the callback info >> >> 2. Either: >> A) Return nil and an NSUserCancelled error. >> B) Return the existing document. >> >> 3. When you get the callback from -canCloseDocument… call super's >> implementation of -openDocumentWithContentsOfURL: >> >> On 5 Jan 2010, at 16:45, Martin Stanley wrote: >> >>> I have a Core-Date application that uses the Cocoa Document architecture >>> (NSPersistentDocument) and would like to ensure that the user only can have >>> 1 document open at a time. Think of this application as similar to Mail.app >>> or Addressbook.app, etc. except that I would like the user to be able to >>> open different persistent stores at will, just not simultaneously. >>> >>> (As an aside, the reason for this is because my document has many related >>> windows and I think it would be confusing for the user. It would not be >>> obvious which auxiliary window relates to which document. I may fix this >>> in the future by using the concept of Inspectors, but at this point I'm not >>> sure if this is the correct model.) >>> >>> I searched extensively and came up with the recommendation that I subclass >>> NSDocumentController and override: >>> - (id)openDocumentWithContentsOfURL:display:error: >>> This was recommended over simply trapping the open menu item(s). >>> >>> >>> This seemed very promising until I ran into a stumbling block. In >>> openDocumentWithContentsOfURL:display:error: I check to see if there is an >>> already open document and if so call: >>> canCloseDocumentWithDelegate:shouldCloseSelector:contextInfo: >>> with an appropriate delegate and selector. The problem is that this returns >>> immediately, even in the case when the document is dirty and it presents a >>> modal dialog to the user. Because of this, the 2nd document is opened >>> before I have a chance to deal with the first one. >>> >>> All of this is making me wonder if I'm taking the wrong approach. >>> >>> Should I figure out a way to prevent the 2nd document from opening before >>> the first one is either saved or abandoned: (override >>> canCloseDocumentWithDelegate:shouldCloseSelector:contextInfo: in my >>> NSPersistentDocument subclass)? This feels like the solution is getting >>> uglier by the minute. >>> >>> Or is there a much easier way to accomplish what I want to do? Or should I >>> be looking at a entirely different approach for my application? >>> >>> Thanks, >>> Martin >>> >>> _______________________________________________ >>> >>> 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/cocoadev%40mikeabdullah.net >>> >>> This email sent to cocoa...@mikeabdullah.net >> > _______________________________________________ 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/archive%40mail-archive.com This email sent to arch...@mail-archive.com
