如何在 Unity C# 中更改我的 TicTacToe 游戏中的移动？

Question

I'm developing a TicTacToe game and faced with a some problem.
After put the "X" I need to change changeMove to true in ChangeMove() function to put next move as "O" in another place. I need to check place.sprite == null too, because I don't want to change put move again.
In the If block I'm changing changeMove to apposite value but it isn't changing(I mean when I'm calling OnMouseDown method second time, I can't get into the else if block). Here is my inspector of MainCamera :

I created a script(PutMove.cs) that inherits all the methods and fields from LogicOfGame.cs besides private bool changeMove only for clickable squares to put move there:
Here is my LogicOfGame.cs, PutMove.cs scripts and inspector of first square:
The square's inspector:

LogicOfGame.cs:

public class LogicOfGame : MonoBehaviour
{
    public SpriteRenderer place;
    private bool changeMove;
    public Image X;
    public Image O;

    public void ChangeMove() 
    {
        if (!changeMove && place.sprite == null)
        {
            place.sprite = X.sprite;
            changeMove = !changeMove;
        }

        else if (changeMove && place.sprite == null)
        {
            place.sprite = O.sprite;
            changeMove = !changeMove;
        }
    }
{

PutMove.cs:

public class PutMove : LogicOfGame
{
    private void OnMouseDown()
    {
        ChangeMove();
    }
}   

I also tried to change changeMove value in another method and call it in OnMouseDown() method, but isn't helped

public bool ChangeMove(bool changeMove) 
{
    return !changeMove;
}

public class PutMove : LogicOfGame
{
    private void OnMouseDown()
    {
        //renamed the ChangeMove()
        //And left only place.sprite = X.sprite;
        PutMove();     
        changeMove = ChangeMove(changeMove);
    }
} 

How can I change value of changeMove at last?

Answer 1

Set a breakpoint and step through the code. When you get to the if/else conditions, is place.sprite == null actually true ? I don't know Unity, but it seems to me this would only be true the first time the method is called. After that, it's set to X.sprite or O.sprite , so subsequent calls would have no affect since the conditions would evaluate to false .

If this is the case, then removing the null check should resolve the issue:

public void ChangeMove() 
{
    if (changeMove) place.sprite = O.sprite;
    else place.sprite = X.sprite;
    changeMove = !changeMove;
}

You may even be able to get rid of the changeMove variable and just examine the value of place.sprite :

public void ChangeMove() 
{
    if (place.sprite == O.sprite) place.sprite = X.sprite;
    else place.sprite = O.sprite;
}

Answer 2

ChangeMove() is only true once, as you set the value of place.sprite as its called the first time, and then it can never be changed again.

As Rufus L says, remove the place.sprite == null condition and there shouldn't be an issue, as it looks like the function (as is) only handles the very first move only.