有一个Objective c基类：

@interface ObjcClass : NSObject {
    NSString *aVariable_;
}

和一个快速的子类：

class SwiftClass : ObjcClass {
    func init() {
        // aVariable_ can't be accessed here. An Objective-c derived
        // class has direct access to it's super's instance variables!
    }
}

我如何ObjcClass aVariable_从内部访问SwiftClass？