Using foreach loop to find GameObjects that are children of something else (Unity3d)

Question

I am making a video game, and while I have an existing code in generic C#, I now have to move it to Unity. I have some basic knowledge with generic C#, but I just started to learn the Unity way of coding.

For starters, I want to write a code that positions all game areas to correct positions, then turn them invisible. Yes, don't be surprised, they need to be all in same places.

Areas can have three size options, I called them Small, Medium and Large. Small and large areas have to be written manually.

 List <GameObject> SmallAreas = new List<GameObject>();

void DefineSmallAreas()
{
    SmallAreas.Add(areaConfirmLoad);
    SmallAreas.Add(areaConfirmQuit);
    SmallAreas.Add(areaConfirmSave);
    SmallAreas.Add(areaGameSaved);
    SmallAreas.Add(areaSave);
    SmallAreas.Add(areaLoad);   
}

Same with large areas.

Now, all other areas, are medium, and there is a large number of them.

So, I want to go through all game objects that are children of "areaContainer", check if their names start with "area", and if they do, I want to add them to MediumAreas list.

That's how I tried it:

void DefineMediumAreas()
{
    GameObject areaContainer = GameObject.Find("areaContainer");

    foreach (GameObject thisObject in areaContainer)
    {
        char[] a = thisObject.Name.ToCharArray();
        if (a.Length >= 4)
        {
        char[] b = { a[0], a[1], a[2], a[3] };
        string thisObjectType = new string(b);
                        (if (thisObjectType == "area")&&(!(SmallAreas.Contains(thisObject))
                        &&(!(LargeAreas.Contains(thisObject)))
                        {
                            MediumAreas.Add(thisObject);
                        }
    }   
}

This however shows an error, that "areaContainer" can't be used that way, I don't have access to Unity now, so can't copy exact message. I think that it's something like "Gameobject doesn't have IEnumerator".

I did try to google for the better approach, and found something called "transform".

 foreach(Transform child in transform)
 {
     Something(child.gameObject);
 }

What I don't understand, is how to use this "transform" in my specific situation.

Please don't get angry at me if this question is silly, I am very new to Unity, and have to learn it from scratch.

And a small second question. Will this work of turning object invisible work:

    foreach(GameObject thisObject in MediumAreas)
    {
        thisObject.position = MediumVector;
        thisObject.GetComponent<Renderer>().enabled = false;
    }

MediumVector is location where the object must be moved to, and it seems to be working.

Answer 1

You can do this: foreach(Transform child in transform)

because the Transform class implements IEnumerable and have some mechanism that enables you to access the child GameObjects with the foreach loop.

---

Unfortunately, you can't do this: foreach (GameObject thisObject in areaContainer)

because areaContainer is a GameObject and this implementation is not done for the GameObject class. That's why you are getting this error:

foreach statement cannot operate on variables of type 'UnityEngine.GameObject' because 'UnityEngine.GameObject' does not contain a public definition for 'GetEnumerator'

To fix it, change your loop to use Transform after finding the GameObject:

GameObject areaContainer = GameObject.Find("areaContainer");
foreach (Transform thisObject in areaContainer.transform){}

The complete code:

List<GameObject> MediumAreas = new List<GameObject>();

void DefineMediumAreas()
{
    GameObject areaContainer = GameObject.Find("areaContainer");
    foreach (Transform thisObject in areaContainer.transform)
    {
        //Check if it contains area
        if (thisObject.name.StartsWith("area"))
        {
            //Add to MediumAreas List
            MediumAreas.Add(thisObject.gameObject);
        }
    }
}