Why is this clearing?

This is driving me crazy. I have this code:

Utilities.getKnockKnockJokes {

            self.previousKnockKnockJoke = self.currentKnockKnockJoke

            print("currentKnockKnockJoke = \(self.currentKnockKnockJoke)")

            self.currentKnockKnockJoke = KnockKnockJokes.knockKnockJokes.randomElement()!

            print("newCurrentKnockKnockJoke = \(self.currentKnockKnockJoke)")

            self.singleServeText.text = self.currentKnockKnockJoke

        }

The function that is called is bellow:

Thank you in advanced!

Clearing what ? What makes you crazy ? What is the point that doesn't work or that you don't understand ?

Sorry my bad, I was going quickly and didn't clarify. This function is running and immediately after, the array that is appended with a joke is cleared and set to nil.

Sorry my bad, I was going quickly and didn't clarify. This function is running and immediately after, the array that is appended with a joke is cleared and set to nil.

Why is this clearing?
 
 
Q