此问题在此处已有答案：

#warning: C-style for statement is deprecated and will be removed in a future version of Swift [duplicate]（4个答案）
六年前就关门了。
我有一些代码在我的项目和下面的代码给予警告;

private var viewController: UIViewController? {
        for var next:UIView? = self.superview; next != nil; next = next?.superview {
            let responder = next?.nextResponder()
            if let vc = responder as? UIViewController {
                return vc
            }
        }
        return nil
    }

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下面的警告行：

for var next:UIView? = self.superview; next != nil; next = next?.superview {

型
我该怎么解决？