[Update: with iOS 8 and iCloud Drive, this is no longer needed as you can access iCloud files across apps now.]
A valid complaint of iCloud is that Mac apps like TextEdit and Preview don’t have iOS versions, so any documents you store in their iCould spaces are not accessible on iOS devices —- only on other Macs. However, I’ve found you can get around this.
- For the iOS app you want to sync with, make sure it is set to be syncing documents with iCloud. For some apps, this is by default, for others, it is an optional setting.
- In the Finder, go to your home folder’s Library folder. Since recent versions of OS X hide this, the easiest way is to go to the Finder and select “Go > Go to Folder …" (or shift+command+G), then type "~/Library" into the box and press Go (or press Enter).
- Scroll down and go into the “Mobile Documents" folder within. In there you will see folders with names ending in apps you have that are syncing documents with iCloud.
- Find the folder for the Mac app you want to sync to the iOS app, and select it. For example, TextEdit is in com~apple~TextEdit. Inside you will see a Documents folder. If you have documents in there, you will need to move them out temporarily. Now, delete this Documents folder.
- Go to the folder for the iOS app you want to connect to the Mac app. For example, Byword on my system is in N39PJFAFEV~com~metaclassy~byword. In there, you will see its Documents folder. Drag this into the Mac app’s folder (com~apple~TextEdit in the example) while holding the Command and Option keys to make an alias (you should get a curved arrow pointer).
- If you had files you moved out of the Mac app’s Documents folder temporarily, you can move them back into the folder, which is now an alias.