2D runner, need a help

I have a script for spawning platforms:

using UnityEngine;

using System.Collections;

 public class SpawnScript : MonoBehaviour {
  
     public GameObject[] obj;
     public float spawnMin = 1f;
     public float spawnMax = 2f;
  
     // Use this for initialization
     void Start ()
     {
         Spawn ();
     }
  
     void Spawn ()
     {
         Instantiate (obj [Random.Range (0, obj.GetLength (0))], transform.position, Quaternion.identity);
         Invoke ("Spawn", Random.Range (spawnMin, spawnMax));
     }
 }

But my platforms spawning or too close to each other, or on each other :( What I need to do that platforms will spawn normally? Not too close to each other and not on each other.