Thanks for posting this. Exploring UIDocument and caching/parsing JSON instead of CoreData for a service based mobile app that must support offline mode ... and looking forward to considering where you landed. On Mon, Mar 21, 2016 at 5:11 PM <davel...@mac.com> wrote:
> > > On Mar 21, 2016, at 2:08 AM, Quincey Morris < > quinceymor...@rivergatesoftware.com> wrote: > > > > On Mar 19, 2016, at 18:54 , davel...@mac.com wrote: > >> > >> What I’m having trouble understanding is how I store the images (whose > filenames will vary from document to document) with NSFileWrapper. In my > top level directory do I have my main model file as a JSON file along with > a file (JSON or plist) that lists all the images and then have an Image > directory that another NSFileWrapper is used to read/write the images (that > are stored in the Image subdirectory)? > >> > >> Or can I simply store all the files without a subdirectory? I still > suspect I need to have a file with a fixed name (such as image.plist) that > tells me what all the other filenames are to put in the NSFileWrapper (vs. > using NSFileManager to ask for the name of all the files). > > > > There’s no correct answer to these questions. It’s a design problem > whose answer is whatever works best in your use case. I’d recommend you > start by choosing what looks to you like the most straightforward approach, > then be prepared to revise your strategy later if it doesn’t work out well. > (The amount of code relating to file wrappers is likely to be small > relative to the code that generally maintains your data model, so rewriting > it shouldn’t be onerous. However, that suggests it would be prudent not to > let the wrappers propagate too deeply into the model. Keep them as an > artifact of the save mechanism in particular, rather than the data model in > general.) > > > > Ok, thanks again for all your feedback. I took a stab at implementing it > yesterday. Everything is in my subclass of UIDocument. The rest of the > model is a layer below the UIDocument subclass (i.e., the subclass has a > couple instance variables which are the main model) although I did put a > few methods in the UIDocument class to add the images since that needs to > change the NSFileWrapper. > > I think I've got it working. Here is how I did it (in case this helps > anyone else and in case anyone else sees a problem with this). > > UIDocument subclass has a NSFIleWrapper instances for each of these: > > 1. Top level NSFileWrapper directory wrapper. > 2. It contains a directory wrapper for a subdirectory named Images where > all the image files (that won't be updated often go). I put the method to > add an image here so that it could update the NSFileWrapper > 3. a NSFileWrapper that contains a single file that is a list of all the > image filenames that is added to the top level NSFileWrapper > 4. a NSFileWrapper for the rest of the model that will change often and is > added to the top level NSFileWrapper > > Whenever an image is added, I remove the NSFileWrapper in #3 from the top > level file wrapper, created a new NSFileWrapper with the new list of > images, and then add that to the top level NSFileWrapper. And add the image > file to the NSFileWrapper in #2. It appears you must call removeFileWrapper > on the top level NSFileWrapper and then add the new NSFileWrapper with > addFileWrapper rather than just calling addFileWrapper with the same > preferred filename and replacement NSFileWrapper. Similarly with my #4 main > data model file, I call removeFileWrapper and addFileWrapper each time a > save occurs since this data changes frequently. > > Since images won't be added as often as the rest of the model is updated, > I'm hoping this won't cause these images to be re-written every time a save > is performed but I'm not certain how to verify this is the case. > > Thanks, > Dave Reed > _______________________________________________ > > 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/lutherbaker%40gmail.com > > This email sent to lutherba...@gmail.com _______________________________________________ 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
