什么是覆盖父Var的正确语法？

Question

目标：使用Swift 3.0.1覆盖UIViewController的transitioningDelegate;基于Objective-C模型。也就是说，将Objective-C转换为其Swift 3.0.1等价物。
Apple transitioningDelegate Reference

的目标C

- (void)setTransitioningDelegate:(id<UIViewControllerTransitioningDelegate>)transitioningDelegate
{
    super.transitioningDelegate = transitioningDelegate;
    self.presentationController.delegate = self;
}

Swift 3.0

这是正确的语法吗？
为什么我收到编译错误？