In order to assist users in accessing Apple's online tools, MacOS prompts users to login to iCloud the first time that they login to a Mac. This can be very helpful for home users, but is largely in the way in multiuser environments, such as most schools. In corporate environments, it can even be against the data management policies (which safeguard the company against data leaks and break-in) or HIPAA or FERPA (depending on the institution.)
To disable the iCloud login prompt, just issue this command on each Mac as its local administrative account:
sudo defaults write /System/Library/User Template/Non_localized/Library/Preferences/com.apple.SetupAssistant DidSeeCloudSetup -bool TRUE
I do this via a shell script in Deploy Studio. In fact, I actually use a really nice script (see link below) with execution delayed until after first restart. This makes sure that the system is booted from the internal drive when the script is executed.
This could also be done by a scripting (or a postflight script in a PKG installer) delivered via Apple Remote Desktop (ARD), Munki, Casper, FileWave, etc. This technique would work well if you needed to implement this change on a set of Macs that were already in service.
If you use ARD, I recommend taking the additional step of adding the script to your setup process in Deploy Studio, Munki, etc. In the case of Munki, Casper, FileWave, etc. you're probably already in good shape. Just see if there is a way to schedule the script too execute early in the list of things to be installed. Otherwise, someone may login to the Mac before the script it loaded. For example, in FileWave you could set to activation date to be before any other filesets.
For a really good implementation of this idea, check out the script on this excellent post. The author does a great job of adjusting every existing user template and account on the Mac. So if you create local accounts (e.g. "student", "teacher", etc.) then this is a way to address that use-case as well. If you use Deploy Studio to image a Mac and CreateUserPKG to create accounts, just be sure to add this script to the workflow after the step with the user packages.
I like this script because it is very adaptable. Whether your accounts are on the local drive or a network system like Open Directory or Active Directory, the script takes it all into account. This reduces the chances of problems if/when you have to change your account management in the future.
