"CloudKit integration requires that all attributes be optional, or have a default value set." If it's not possible anymore to set a default value, the only way for CloudKit would be setting all members to "optional". Really?

Awesome! Thank you so much!

If you can't "see" your app on the device just goto Xcode > Devices & Simulators > Select your connected device > Installed Apps > Selected your App and remove it (-). Try installing again.

Spent hours about this topic (EditButton...) This was the only solution that worked in my case. Thank you!