A Simple Unity UI Canvas Fading In / Out C# Script. Useful for transitions.

CanvasFaderScript.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

/*
 * A Simple Canvas Fader Script (Unity 5.6)
 * 
 * 
 * Uses : Fade out or Fade In a UI Canvas. Not for transitioning a whole Scene with elements. 
 * 
 * Usage : Add a Canvas Group Component to the UI Canvas. Add this script to the canvas. Add the function for onComplete.
 * 
 * modified : 15/5/2017
 * by Monster Brain Games (monsterbraininc.com)
 * 
 */

public class CanvasFaderScript : MonoBehaviour {
	enum eFadeType{
		fade_in,
		fade_out
	};

	private float _alpha=1.0f;

	private bool _isFading=false;

	[SerializeField]
	private eFadeType fadeType = eFadeType.fade_in;
	[SerializeField]
	private float fadingDuration = 1.0f;	//Time for fading
	private float fadeSpeed = 1.0f;

	[SerializeField]
	private bool _startFadeOnAwake=false;

	[SerializeField]
	private UnityEvent onCompleteEvent;

	private CanvasGroup _canvasGroup;

	void Awake(){
		if (fadeType == eFadeType.fade_in)
			_alpha = 0;
		else if (fadeType == eFadeType.fade_out)
			_alpha = 1.0f;

		_canvasGroup = GetComponent<CanvasGroup> ();
		if (_canvasGroup == null)
			Debug.LogError ("[warning] CanvasFadeScript: please add a Canvas Group to the Canvas");

		if (fadingDuration > 0)
			fadeSpeed = 1 / fadingDuration;

		if (_startFadeOnAwake)
			StartFading ();
	}

	// Use this for initialization
	void Start () {
		
	}

	public void StartFading(){
		setCanvasAlpha ();
		_isFading = true;
	}

	void setCanvasAlpha ()
	{
		if(_canvasGroup != null) _canvasGroup.alpha = _alpha;
	}
	
	// Update is called once per frame
	void Update () {
		if (_isFading) {
			if (fadeType == eFadeType.fade_in) {
				_alpha += Time.deltaTime * fadeSpeed;
				if (_alpha > 0.95f)
					onFadeCompleted ();
			} else if (fadeType == eFadeType.fade_out) {
				_alpha -= Time.deltaTime * fadeSpeed;
				if (_alpha < 0.05f)
					onFadeCompleted ();
			}

			setCanvasAlpha ();
		}
	}

	public void onFadeCompleted(){
		_isFading = false;

		//Call On Complete Here
		if (onCompleteEvent != null)
			onCompleteEvent.Invoke ();
	}
}