Error i swift code

I am dabbling at swift currently (somewhat of a noob) and found out that I’ve got an error on one of the codes. It is in the “cardButton” with the following error message:
@IBAction func cardButtonHandle(_ sender: Any) {
cardButton.isEnabled = true
if questionIdx < count(mcArray) - 1 { //error here
questionIdx += 1 //
} else {
questionIdx = 0
}
nextQuestion()
}
Any help with this particular code would be really helpful!

Hey there!
Hope this code helps
it should be

  1. if questionIdx < (mcArray!.count) - 1 { //error here