URLForUbiquityContainerIdentifier returns nil even if configured correctly

Question

I am having the problem, that URLForUbiquityContainerIdentifier is returning nil in some cases even if the user has set up everything correctly in the settings. My code:

Answer 1

Today I experienced this problem again.

This time it was because I had an invalid provisioning profile.

On the developer site, I had to generate a new provisioning profile. Afterward reload the provisioning profiles within Xcode5. Now URLForUbiquityContainerIdentifier again returns valid urls.

Answer 2

Enable "iCloud Drive" in the iPhone's Settings