Simple set of coroutine helpers and tweening functions

Tween.cs

using UnityEngine;
using System.Collections;

public static class Tween
{
  public static IEnumerator Tween(float duration, System.Action<float> tweenFunc)
  {
    for (float timer = 0; timer < duration; timer += Time.deltaTime)
    {
      tweenFunc?.Invoke(timer / duration);
      yield return null;
    }

    tweenFunc?.Invoke(1);
  }

  public static IEnumerator TweenUnscaled(float duration, System.Action<float> tweenFunc)
  {
    for (float timer = 0; timer < duration; timer += Time.unscaledDeltaTime)
    {
      tweenFunc?.Invoke(timer / duration);
      yield return null;
    }

    tweenFunc?.Invoke(1);
  }
  
  public static IEnumerator WaitForTime(float duration)
  {
    for (float timer = 0; timer < duration; timer += Time.deltaTime)
    {
      yield return null;
    }
  }

  public static IEnumerator WaitForTimeUnscaled(float duration)
  {
    for (float timer = 0; timer < duration; timer += Time.unscaledDeltaTime)
    {
      yield return null;
    }
  }

  // Usage: yield return WaitForEvent(f => MyEvent += f, f => MyEvent -= f)
  public static IEnumerator WaitForEvent(System.Action<System.Action> subscribeDelegate, System.Action<System.Action> unsubscribeDelegate)
  {
    bool invoked = false;

    System.Action listener = () => invoked = true;

    subscribeDelegate?.Invoke(listener);

    // Wait for event
    while (!invoked)
      yield return null;

    unsubscribeDelegate?.Invoke(listener);
  }

  public static IEnumerator WaitForEvent<T>(System.Action<System.Action<T>> subscribeDelegate, System.Action<System.Action<T>> unsubscribeDelegate)
  {
    bool invoked = false;

    System.Action<T> listener = (obj) => invoked = true;

    subscribeDelegate?.Invoke(listener);

    // Wait for event
    while (!invoked)
      yield return null;

    unsubscribeDelegate?.Invoke(listener);
  }

  public static IEnumerator WaitForEvent<T1, T2>(System.Action<System.Action<T1, T2>> subscribeDelegate, System.Action<System.Action<T1, T2>> unsubscribeDelegate)
  {
    bool invoked = false;

    System.Action<T1, T2> listener = (a, b) => invoked = true;

    subscribeDelegate?.Invoke(listener);

    // Wait for event
    while (!invoked)
      yield return null;

    unsubscribeDelegate?.Invoke(listener);
  }
}