Question

I have a singleton class called playbackhelper to which I want to add a member that is a reference to a viewcontroller. But I don’t think I can make the member a reference because I want to be able to change which controller I’m linking to and I don’t think that’s possible with a reference.

This is my controller:

@interface InstrumentGridViewController : UIViewController {

}
-(void) someMethod;
@end

And this is my singleton class on which I want a member that is some kind of pointer to the controller.

class PlaybackHelper{

private:

    // Singleton methods
    PlaybackHelper();
    PlaybackHelper(PlaybackHelper const&);
    void operator=(PlaybackHelper const&);

public:

    static PlaybackHelper &getInstance();

    // ((((some InstrumentGridViewController member here))))
    InstrumentGridViewController controllerMember;
}

So my question is: how can I link those with each other/how do I make a member that points to the controller and how should it be initialized?

EDIT: Basically I want to be able to call the controller methods from the singleton class, like this:

[PlaybackHelper::getInstance().controllerMember someMethod];

But I don’t know how to set my singleton up to make this possible. The way it is set up in the example right now controllerMember would be a copy of the controller object which is not what I want.

Answer 1

Debates about singleton use aside, if you are using ARC, you can easily use ObjC objects inside C++ classes, and memory management is taken care of.

If you want to make it an accessor…

class PlaybackHelper{
private:
    // ... other stuff...
    InstrumentGridViewController *_instrumentGridViewController;

public:
    InstrumentGridViewController *controllerMember() {
        return _instrumentGridViewController;
    }
};


[PlaybackHelper::getInstance().controllerMember() someMethod];

If you just want to make it a public member…

class PlaybackHelper{
public:
    InstrumentGridViewController *controllerMember;
};


[PlaybackHelper::getInstance().controllerMember someMethod];

ObjC objects are recognized to have non-trivial ctor/dtor, and the compiler will automatically take care of the ARC stuff.

LLVM + ARC + C++ makes it easy to mix ObjC objects with C++. In fact, you can do this without worrying a bit…

std::vector<UIView*> listOfViews;

All the memory management is magically arranged by the compiler.