TextFileHandler.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class TextFileHandler : MonoBehaviour {

    public GameObject diaglogBox;
    public Text dialogText;

    public TextAsset textFile;
    public string[] textLines;

    public int currentLine;
    public int endLine;

    private bool isActive;

    public Transform player;
    public Transform target;


    void Start () {

        // disable dialogbox at start
        diaglogBox.gameObject.SetActive(false);

        
        if (textFile != null) {
            textLines = textFile.text.Split('\n');
        }


        // If line ending is not manually set to certain number
        // set line ending to the size of array -1 because array's index starts with 0
        if (endLine == 0) {
            endLine = textLines.Length - 1;
        }
     
	
	}// end Start()

   

    void Update() {


        dialogText.text = textLines[currentLine];


        if (Input.GetKeyDown("e")) {

            currentLine++;

        }



        if (target) {
            float dist = Vector3.Distance(target.position, player.position);
            if (dist < 2.0f) {
                isActive = true;
            }
            else {
                isActive = false;
            }

        }


        if (isActive) {

            diaglogBox.gameObject.SetActive(true);

            if (currentLine == endLine) {
                diaglogBox.gameObject.SetActive(false);

            }

        }
        else {
            diaglogBox.gameObject.SetActive(false);
        }


    }//end Update()

}//end