在 Unity (C#) 中隐藏和显示按钮

Question

I have a button (in UI), that I want to hide sometimes (but show again later), which means that it shouldn't show anymore and I shouldn't be able to click it. The only solution I found (that has actually managed to hide the button), is SetActive() .

But in Update() , when I do SetActive(false) (the true/false is controlled with the variable wave_happening in my script), Update() doesn't run anymore, so I can't set it to true again. When I do GameObject.Find("Start Button").SetActive(true) in another script, it just gives me a NullReferenceException (Object reference not set to an instance of an object).

This is my Update() function:

void Update() {
    wave_happening = enemy_spawner_script.wave_happening;
    Debug.Log(wave_happening);
    transform.gameObject.SetActive(wave_happening);
}

Is there a solution to stop this problem, or another way to hide a button?

I'm fairly new to Unity and C#, so I don't know very much.

Answer 1

You can try disabling the button's rendering and functionality components:

GetComponent<Button>().enabled = false; // remove functionality

GetComponent<Image>().enabled = false; // remove rendering

Now, adding that to your Update function, plus a few changes for performance so you are not enabling/disabling every single frame, only when needed:

private bool isShowing = true; // or whatever your default value is

void Update() {
    wave_happening = enemy_spawner_script.wave_happening;
    Debug.Log(wave_happening);
    
    if(wave_happening != isShowing) {
        show(wave_happening);
        isShowing = wave_happening;
    }
}

void show(bool isShow) {
    GetComponent<Button>().enabled = isShow; // remove functionality

    GetComponent<Image>().enabled = isShow; // remove rendering
}

Answer 2

It's really difficult to do this well. Lots of issues arise:

• Inevitably the button will be in a H or V layout group, and, as a basic software engineering issue of course you want it to work whether or not it is in a layout group, as that layout detail may be changed by your designers as the project goes on. For this reason it is a really good idea, as the OP initially guessed, to simply use .SetActive

• But then you have the problem of the button being off so Update is not running. A simple solution is just to put the button in a wrapper. That is to say, simply in a UI Panel . Have the button manager script on that wrapper rather than on the button per se.

Then you just have a pretty Property on the manager script,

public bool Showme
{
    etc...

and then you can just go...

void Update()
{
    Showme = enemy_spawner_script.wave_happening;
}

Can't get simpler looking code.

• However, if you use a wrapper Panel. It is true that you have to be pretty expert at using the UI (particularly the auto sizing stuff) to make it work just the way you want. But, that's part of building Unity expertise unfortunately. :/

• The concerns about performance is... truly ridiculous. There's no difference between Unity's raw code "checking a boolean" and yourself "checking a boolean". However for sure as a matter of style it's crap to poll it in Update. (Note that in point "B" just above, if you're going to have heinously ugly "anti-polling" code, bury it in that Property.)

And then...

"Trick" solution

• A tip in Unity UI is you can add a CanvasGroup anywhere. Why would you do this? It allows you to FADE the whole thing, which, is often a quick solution to achieve what you want.

Hence..

public CanvasGroup fader;

and then..

void Update()
{
    fader.alpha = enemy_spawner_script.wave_happening ? 1f : 0f;
}

and you're done!