Simple script for fading any UI image in unity.

FadeAnyImage

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class FadeAnyImage : MonoBehaviour {

	float timePassed = 0;
	float totalFadeLength;
	Image imageToFade;
	AnimationCurve curve;

	public void Fade (Image img, float fadeLength, AnimationCurve animCurve)
	{
		timePassed = 0;
		totalFadeLength = fadeLength;
		imageToFade = img;
		curve = animCurve;
	}

	void Update ()
	{
		timePassed += Time.deltaTime;

		Color temp = imageToFade.color;
		temp.a = curve.Evaluate(timePassed/totalFadeLength);
		imageToFade.color = temp;


		if (timePassed / totalFadeLength > 1)
		{
			Destroy(this);
		}

	}


}

To use this script you simple need to instantiate the script and then call the function Fade()

gameObject.AddComponent<FadeAnyImage>();
GetComponent<FadeAnyImage>().Fade(splashImage, splashLength, curve);