The script below works, but it does not fade, it just jumps straight to the color.
using UnityEngine;
using System.Collections;
public class Ladder : MonoBehaviour {
public float smooth = 50;
public Color transparent = new Color(1f,1f,1f,0f);
public Color visible = new Color(1f,1f,1f,1f);
public SpriteRenderer fadeimage;
public GameObject boy;
// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
}
void OnTriggerEnter2D(Collider2D other)
{
StartCoroutine ("fade");
boy.transform.position = new Vector2 (8f, 11f);
}
public IEnumerator fade(){
fadeimage.color = Color.Lerp (transparent, visible,Time.deltaTime * smooth);
yield return new WaitForSeconds (1);
fadeimage.color = Color.Lerp (visible, transparent,Time.deltaTime * smooth);
}
}
How can I make it fade? Thanks in advance! 
I’m not sure if you fully understand how lerping and coroutines work. A lerp is something which can happen over a period of time between the values (percentages) of 0 and 1. Unity tutorial link. Your coroutine doesn’t update anything for an entire second. Coroutines can BASICALLY behave like a second Update() function or a secondary thread. Unity tutorial link.
private IEnumerator Update_Fade()
{
float timer = 0.0f;
float time = 1.0f;
while(timer <= time)
{
timer += Time.deltaTime;
float lerp_Percentage = timer / time;
fadeimage.color = Color.Lerp(transparent, visible, lerp_Percentage);
yield return null;
}
}
I wasn’t actually going to write you a solution, because I believe you need to understand first how both methods work, but I hope you won’t just copy and paste the answer but actually take the time to understand what’s happening. Because this type of function is something I personally use EVERYWHERE. But to do so, you need to understand! Hope it helps!