Convert Keyboard controlls to UI Buttons

Does anybody know how to convert this keyboard controlls to ui buttons controlls or touch controlls.
This is a 2d game.

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {

public float maxSpeed = 6f;
public float jumpForce = 1000f;
public Transform groundCheck;
public LayerMask whatIsGround;
public float verticalSpeed = 20;
[HideInInspector]
public bool lookingRight = true;
bool doubleJump = false;
public GameObject Boost;

private Animator cloudanim;
public GameObject Cloud;

private Rigidbody2D rb2d;
private Animator anim;
private bool isGrounded = false;

// Use this for initialization
void Start () {
	rb2d = GetComponent<Rigidbody2D>();
	anim = GetComponent<Animator>();
	//cloudanim = GetComponent<Animator>();

	Cloud = GameObject.Find("Cloud");
	//cloudanim = GameObject.Find("Cloud(Clone)").GetComponent<Animator>();
}

void OnCollisionEnter2D(Collision2D collision2D) {
	
	if (collision2D.relativeVelocity.magnitude > 20){
		Boost = Instantiate(Resources.Load("Prefabs/Cloud"), transform.position, transform.rotation) as GameObject;
	//	cloudanim.Play("cloud");	

	}
}


// Update is called once per frame
void Update () {

if (Input.GetButtonDown("Jump") && (isGrounded || !doubleJump))
	{
		rb2d.AddForce(new Vector2(0,jumpForce));

		if (!doubleJump && !isGrounded)
		{
			doubleJump = true;
			Boost = Instantiate(Resources.Load("Prefabs/Cloud"), transform.position, transform.rotation) as GameObject;
		//	cloudanim.Play("cloud");		
		}
	}

if (Input.GetButtonDown("Vertical") && !isGrounded)
	{
		rb2d.AddForce(new Vector2(0,-jumpForce));
		Boost = Instantiate(Resources.Load("Prefabs/Cloud"), transform.position, transform.rotation) as GameObject;
		//cloudanim.Play("cloud");
	}

}

void FixedUpdate()
{
	if (isGrounded) 
		doubleJump = false;

	float hor = Input.GetAxis ("Horizontal");

	anim.SetFloat ("Speed", Mathf.Abs (hor));

	rb2d.velocity = new Vector2 (hor * maxSpeed, rb2d.velocity.y);
	  
	isGrounded = Physics2D.OverlapCircle (groundCheck.position, 0.15F, whatIsGround);

	anim.SetBool ("IsGrounded", isGrounded);

	if ((hor > 0 && !lookingRight)||(hor < 0 && lookingRight))
		Flip ();
	 
	anim.SetFloat ("vSpeed", GetComponent<Rigidbody2D>().velocity.y);
}


public void Flip()
{
	lookingRight = !lookingRight;
	Vector3 myScale = transform.localScale;
	myScale.x *= -1;
	transform.localScale = myScale;
}

}