Common iCloud container between Mac and iOS app?

Question

I want to build an iCloud based app that runs on both the Apple platforms, iOS and Mac. The app will use UIDocument on iOS and NSDocument on Mac to have a document based synchronization model - documents created on iOS will be available on Mac and vice versa.

The particular problem I'm facing is that I want the same iCloud container on both the apps. XCode creates a default container for the app based on the App ID, which has to be different on both the apps because this seems to be an Apple requirement - no two apps can have the same app id even if they are on different platforms.

So I left the default created container alone and added another container on both the Mac app as well as the iOS app. The app seems to work fine, I can create a new file package in both the apps in the correct place, but I'm having 2 issues:

1. The container does not appear properly in the iCloud settings management screen. In the entitlements section in XCode, I named the container as com.mycompany.myapp.mycontainer in both the apps. In the settings screen in iOS (Settings -> General -> Usage -> Manage Storage -> Show All) my app is listed as "mycontainer" instead of the App's actual name as I expected. Is it possible to supply a name and icon in the App's Info.plist to make it list properly?

2. My NSMetadataQuery is not working properly. I had made the iOS app with the Empty Application template, so the Info.plist was not properly setup with the CFBundleDocumentTypes key but I figured that out and fixed it. For firing my NSMetadataQuery in the iOS app, I'm using:

   [self.queryCloud setPredicate:[NSPredicate predicateWithFormat:@"%K like '*.myextension*'",NSMetadataItemFSNameKey]];

   with the search scope set like this:

   [self.queryCloud setSearchScopes:[NSArray arrayWithObjects:NSMetadataQueryUbiquitousDocumentsScope, NSMetadataQueryUbiquitousDataScope, nil]];

I run the query after establishing the container's URL, I get the started and finished gathering notifications, but never the update notification from the NSMetadataQuery. Unless I go ahead and create a new document. If I create the document then I get notifications for Update, but only in that session. Next time I start up the app, the same settings don't give me any update notifications from NSMetadataQuery.

What am I doing wrong? Any pointers to articles on creating an iCloud document app targeting both Mac and iOS would be much appreciated! Suggestions, thoughts are most welcome.

Answer 1

I don't know about your NSMetadataQuery issues, but adding a shared iCloud container is easy, as long as you get the gotcha:

1. Pick one app ID that will be your shared cloud container. Doesn't matter if iOS or Mac OS X, you need to publish this app and it must be approved from the Apple Review Team* before your iCloud container will be available to any other app. e.g.

    com.company.myawesomeapp
   

2. Note that you must not use a container name after your app ID (com.company.myawesomeapp.cloudcontainer), just use your appID!

3. Pick a second app ID (doesn't really matter), and create your second app. Open up Xcode and enable iCloud in the Capabilites Pane. Then under "iCloud Container Identifiers", add the identifier of your first (published and approved!) app

    com.company.myawesomeapp
   

That's it! There's just this one catch and that's the bottom line:

In order to use a container, an app must be available and approved. Before approval no other app may access your container, because technically it only exists as soon as your app is approved. Actually, it doesn't have to be available in the AppStore, it just needs to be approved (can be on developer held release).

You can only use a (shared) iCloud container if your app is published and has been approved.