How do I shoot using buttons for ios

Hey, I'm still pretty new to unity game developing, I am currently making a game where you need to shoot upwards, the game is in 2D and I am going to use buttons since it will be an ios game and I want to make it shoot using a button. I want to know how to do it. This is my code so far.

{

 public float speed = 50.0f;
 private Rigidbody2D rb;
 private Vector2 screenBounds;
 // Start is called before the first frame update
 void Start()
 {
     rb = this.GetComponent<Rigidbody2D>();
     rb.velocity = Vector2.up * speed;
     screenBounds = Camera.main.ScreenToWorldPoint(new Vector3(Screen.width, Screen.height, Camera.main.transform.position.z));
 }

 // Update is called once per frame
 void Update()
 {
     if(transform.position.y < 0){
         Destroy(this.gameObject);
     }
 }

}