Is there a way to get iOS to prompt for CKApplicationPermissionUserDiscoverability again after the user has declined it? The most I've been able to do is remove permission in the iCloud settings pane in OS X, which just returns a deny to the iOS app without any user interaction. The app I'm writing is useless without discoverability, so I want to be able to prompt again if the user initially says no.
On the iCloud settings of the iOS 8.1, under the iCloud Drive, there is an option called "Look Me Up By Email". There you will be able to reset the permission.
In iCloud dashboard, under deployment, reset the development environment, and the next time you install the app, it will prompt again for the permission.
Warning: resetting the development environment will delete all existing records AND it will reset the record definitions to what is deployed to the production environment. So if you haven't deployed to production environment yet you can loose all your record types and custom fields in Users. I recommend deploying to production even if it's not final, then resetting.
You can't reactivate the system prompt. What you can do is test for the permissions and if it's not ok supply your own prompt asking the user to go to the settings to change the permissions.
来源：https://stackoverflow.com/questions/26487535/how-to-prompt-for-ckapplicationpermissionuserdiscoverability-again