Random number between 0 and textbox text

So I want to generate a random number between 0 and numberTextBox.text.

Let's say that the textbox text is 5, then i want to generate a random number between 0 and 5.

I have now:

@IBAction func nextButton(sender: AnyObject) {
let MaxNumber = numberTextBox.text
let randomNumber = random(); MaxNumber

var textString = String(randomNumber)
numberLabel.text = textString
}

But when I test the application, and type 5 in the textBox, the numberLabel.text is something like 192819371.. It's very high.