MeterSticker.cs

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

[Script(ScriptRole.View)]
public class MeterSticker : Sticker
{
    public float Value = 1;
    public Gradient ColorRamp;
    public float EaseFactor = 10;
    [Range(0, 1)]
    public float FillAlpha;

    float _displayedValue = 1;
    Image _fill;

    protected override void Awake()
    {
        base.Awake();
    }

    protected override void OnSpawn()
    {
        base.OnSpawn();

        _fill = _guiObject.transform.FindChild("fill").GetComponent<Image>();
        _guiObject.SetActive(IsVisible);
    }

    protected override void Update()
    {
        base.Update();

        _displayedValue = Mathf.Lerp(_displayedValue, Value, Time.deltaTime * EaseFactor);
        Color color = ColorRamp.Evaluate(_displayedValue);
        color.a = FillAlpha;
        _fill.color = color;
        _fill.fillAmount = _displayedValue;
        _guiObject.SetActive(IsVisible);
    }

    protected override void OnDestroy()
    {
        base.OnDestroy();

        // Check if the GUI Object is null before destroying it.
        // In the case of Scene unloading, the GUI Object can actually be destroyed before it's owner.
        if (_guiObject != null)
            Destroy(_guiObject);
    }
}