Variable nil in one function

Question

I'm using latest Xcode Version 8.0 (8A218a) and Swift 3.0.

I'm working with a UIScrollview (m_scrollView) that is correctly allocated and used.

When callbackForceUpdateEvent is called, m_scrollView is OK but right after, when calling showEvents I got the error: fatal error: unexpectedly found nil while unwrapping an Optional value when trying to print its description (A). I also got this error if I try to access its subviews(B). But, I can add subviews to it (C), and it's displayed correctly. Only printing its description or accessing its subviews failed.

override func callbackForceUpdateEvent(_ event: Event) {

        print (self.m_scrollView) // works fine

        self.showEvents()
    }

func showEvents() {
     /*(A)*/ print (self.m_scrollview) // fatal error: unexpectedly found nil while unwrapping an Optional value

     /*(B)*/ for view in m_scrollview.subviews { // fatal error: unexpectedly found nil while unwrapping an Optional value
     }

     /*(C)*/ m_scrollView.addSubview(v) // works fine !!!
}

It's driving me crazy since 2 days now.

Answer 1

I tried to rename my variable and it's working fine now. And I understood my mistake: the variable m_scrollview was also declared in the superclass.

I don't know why the Swift compiler didn't tell me that. But after renaming back the variable, Swift told me it...

Problem solved!