I this FAQ it says:
What happens when I turn off iCloud Keychain on a device?
When you turn off iCloud Keychain for a device, you're asked to keep or delete the passwords and credit card information that you saved. If you choose to keep the information, it isn't deleted or updated when you make changes on other devices. If you don't choose to keep the information on at least one device, your Keychain data will be deleted from your device and the iCloud servers.
So understand data stored by the user such as passwords is removed. What about data stored by an app installed on an iOS device? Is it removed as well?
Can we assume that data stored in the keychain will not be removed by other means external to the app, or should we plan our app to handle such situation?