如何增加数字但不是立即增加(使用Unity Engine)

using UnityEngine;
using UnityEngine.UI;

public class NumberIncrease : MonoBehaviour
{
    public Text displayText;    // 文本框显示数字的UI元素
    public int targetNumber;    // 目标数字
    public float increaseRate;  // 数字增加的速率
    public float delayTime;     // 延迟时间

    private int currentNumber;  // 当前数字
    private float timer;        // 定时器

    private void Start()
    {
        currentNumber = 0;
        timer = delayTime;
    }

    private void Update()
    {
        timer -= Time.deltaTime;
        if (timer <= 0f)
        {
            IncreaseNumber();
            timer = delayTime;
        }
    }

    private void IncreaseNumber()
    {
        if (currentNumber < targetNumber)
        {
            currentNumber++;
            displayText.text = currentNumber.ToString();
        }
    }
}