The code to check and bail out if a string is NULL or empty most of the time looks something like that:

if self.text == nil || self.text!.isEmpty  {
    return
}

In Swift, we have a syntax candy called guard that executes statements based on a Boolean value of an expression. With guard in mind we can re-write the code above:

guard let gText = self.text where !gText.isEmpty else {
    return
}

Of course the question is whether using guard makes the code cleaner or more confusing.

It is up to you to decide!