There are two different ways you might go about this.
1) The data you need to share is non-persistent. In other words you need to launch one application with a piece of data that it can do something with. In this case you would register a special URL scheme per application.
You can find out more information about URL schemes via Craig Hockenberry in his [redacted] blog post.
2) The data you need to share is persistent. In other words you need something like a data file that both applications can read and write too. As far as I know there isn't a safe way to do this other than storing your data on a remote server. If you need the data accessible without a data connection then you would need to figure out a way to sync data between the individual apps and the remote server.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…