[Unity 5.2] UGUI Buttons! Cant add a Listener.

Questions & Answers
1

Hello everyone, I’m currently having an issue with Unity and it’s buttons.
I am procedurally instantiating buttons on a page in correspondence with the amount of files in a save directory, problem is that I need a way for the player so tell the game which save they want to load.
The Issue lies when I try to add a Listener to each button that is instantiated.

if (Mode == "Load")
  {
     while (l < 8)
        {
          //Get the ContentHolder's Position
          Vector3 ContentHolderPos = ContentHolder.transform.position;
          //Instantiate the Button and assign a new name, instanceID and a random set of 4 numbers.
          string k = Instantiate(TextPrefab, new Vector3(142.95598f, listlength + 308, 0), Quaternion.Euler(0, 0, 0)).name = "TextPrefab" + GetInstanceID() + Random.Range(0,1000);
          //Set the Parent
          GameObject.Find(k).transform.parent = ContentHolder.transform;
          //Set the Scale
          GameObject.Find(k).transform.localScale = new Vector3(1,1,1);
          //GameObject.Find(k).transform.GetChild(0).GetComponent<Button>().onClick.RemoveAllListeners();
          //Add the Listener:
          GameObject.Find(k).transform.GetChild(0).GetComponent<Button>().onClick.AddListener(() => ButtonCall());
          //Log Stuff
          Debug.LogError("Tried to add a Listener to " + GameObject.Find(k).name + "'s " + GameObject.Find(k).transform.GetChild(0).name);
          //Add to the Listlength Counter
          listlength = listlength - 10;
          //Add to the Loop Counter
          l++;
      }
   }
}

As you can see, it’s a bit messy, I hope it’s readable.
I’ve marked the section where the button is instantiated then the button is retrieved and the listener is added.
On Play: It makes a series of 8 buttons and does not add a listener to each of them.

2

I’m not sure how your prefab is set up but the fault might be in the GetChild method depending on the parent/child relationships you have your GameObjects in. You could try using GetComponentInChildren instead to get the button directly from the parent or grandparent. Also, as a general rule of thumb the GameObject.Find function is rather slow so it’s advisable to store local references to GameObjects to re-use whenever possible. You might try something like this:

if (Mode == "Load")
{
    while (l < 8)
    {
        Vector3 ContentHolderPos = ContentHolder.transform.position;
        GameObject newButton = (GameObject)Instantiate(TextPrefab, 
               new Vector3(142.95598f, listlength + 308, 0), Quaternion.Euler(0, 0, 0));
        newButton.name = "TextPrefab" + GetInstanceID() + Random.Range(0, 1000);
        newButton.transform.parent = ContentHolder.transform;
        newButton.transform.localScale = new Vector3(1, 1, 1);
        newButton.transform.GetComponentInChildren<Button>()
                            .onClick.AddListener(() => ButtonCall());
        listlength -= 10;
        l++;
    }
}