Check out example codes for "unity mobile controls". It will help you in understanding the concepts better.

Code Example 1

using System.Collections; using System.Collections.Generic; using UnityEngine;  public class Movement : MonoBehaviour { 	//variables 	public float moveSpeed = 300; 	public GameObject character;  	private Rigidbody2D characterBody; 	private float ScreenWidth;   	// Use this for initialization 	void Start () { 		ScreenWidth = Screen.width; 		characterBody = character.GetComponent<rigidbody2d>(); 	} 	 	// Update is called once per frame 	void Update () { 		int i = 0; 		//loop over every touch found 		while (i < Input.touchCount) { 			if (Input.GetTouch (i).position.x > ScreenWidth / 2) { 				//move right 				RunCharacter (1.0f); 			} 			if (Input.GetTouch (i).position.x < ScreenWidth / 2) { 				//move left 				RunCharacter (-1.0f); 			} 			++i; 		} 	} 	void FixedUpdate(){ 		#if UNITY_EDITOR 		RunCharacter(Input.GetAxis("Horizontal")); 		#endif 	}  	private void RunCharacter(float horizontalInput){ 		//move player 		characterBody.AddForce(new Vector2(horizontalInput * moveSpeed * Time.deltaTime, 0));  	} }

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