相关疑难解决方法(0)

我正在尝试进行此扩展:

extension UIViewController
{
    class func initialize(storyboardName: String, storyboardId: String) -> Self
    {
        let storyboad = UIStoryboard(name: storyboardName, bundle: nil)
        let controller = storyboad.instantiateViewControllerWithIdentifier(storyboardId) as! Self

        return controller
    }
}

但我得到编译错误:

错误:无法将'UIViewController'类型的返回表达式转换为返回类型'Self'

可能吗？我也想成为init(storyboardName: String, storyboardId: String)