As you may know we have the classes for iCloud in our plugins for some time now. You can find them here in the documentation. But to use them you first need to sell your app through the Mac App Store and second you need to work through all the certificates, provision profiles and entitlements. So I know a few people use this all with our plugins, but we missed an example project.
So 12.1pr5 plugins later today contain example projects. You can't run them directly as you need a Mac Developer account and create yourself certificates and profiles. We include sample project, but you have to replace our IDs with yours. Once you got it working, you can send push notifications and receive them in the test application. Also you can put a file into iCloud and fine files in the cloud.
Our examples are a starting point. They are not yet complete and we happily extend them based on your input. But already with that example we can upload a jpeg file and get it's URL for sharing. This published URL can be send by email to someone who can download this image file from the cloud. Download MBS logo jpeg file from iCloud.