在运行时创建的哪个切换已在Unity中调用？

Question

I need to create a set of Toggle at run-time and set a listener when one of those change. So this implies to know who changed.

I see how to do it statically in the UI but not programmatically and it's hard to find documentation on this subject.

Answer 1

The Toggle.onValueChanged event is used to subscribe to the Toggle event to detect when it is toggled. Toggle.toggle.isOn is used to check the status of the toggle. Use AddListener and delegate to help register the toggle so that you will get the name of the toggle when it is toggled:

public Toggle toggle1;

void OnEnable()
{
    //Register Toggle Events
    toggle1.onValueChanged.AddListener(delegate
    {
        ToggleCallValueChanged(toggle1);
    });
}

private void ToggleCallValueChanged(Toggle toggle)
{
    Debug.Log("Toggle: " + toggle + " is " + toggle.isOn);
}

void OnDisable()
{
    //Un-Register Toggle Events
    toggle1.onValueChanged.RemoveAllListeners();
}

If using multiple toggles, you can also re-use that one function but use the if statement to determine which one is toggled. You do this if the toggles are related. This is better than creating a new callback function for each toggle control.

Example of 3 toggles detected with one function:

public Toggle toggle1;
public Toggle toggle2;
public Toggle toggle3;

void OnEnable()
{
    //Register Toggle Events
    toggle1.onValueChanged.AddListener(delegate { ToggleCallBack(toggle1); });
    toggle2.onValueChanged.AddListener(delegate { ToggleCallBack(toggle2); });
    toggle3.onValueChanged.AddListener(delegate { ToggleCallBack(toggle3); });
}

private void ToggleCallBack(Toggle toggle)
{
    if (toggle == toggle1)
    {
        //Your code for Toggle 1
        Debug.Log("Toggled: " + toggle1.name);
    }

    if (toggle == toggle2)
    {
        //Your code for Toggle 2
        Debug.Log("Toggled: " + toggle2.name);
    }

    if (toggle == toggle3)
    {
        //Your code for Toggle 3
        Debug.Log("Toggled: " + toggle3.name);
    }
}

void OnDisable()
{
    //Un-Register Toggle Events
    toggle1.onValueChanged.RemoveAllListeners();
    toggle2.onValueChanged.RemoveAllListeners();
    toggle3.onValueChanged.RemoveAllListeners();
}

Answer 2

You can use what is called an Observer pattern . That's many systems of events work.

Basically, each of your toggles created is able to send some event "I was toggled" (with giving some ID, name, value, etc.... to some object that has subscribed to it.

It also has a function "subscribe" or "attach", that allows any object to subscribe to it at runtime.

When you subscribe, you provide a callback function (which what could be called and event handler , if you have already heard the term).

That function is what will happen when the toggled is used : it will simply look at the list of object that has subscribe to it, and call the callback on each of them. That's the way with which the toggle will communicate the event.

Basically, in your case, you probably will have simple one controller which will subscribe to the toggle. This controller could be (but not necessarily) the class that created the toggles at the first place.

The whole pattern is useful because there is absolutely no need for the toggles to be aware of each other or of the controller in their code, (low coupling). And you never have to constantly check if something has changed, the "information" is properly sent only when relevant.

See Programmers's answer for a possible implementation.