Need to set position z to 0

Question

I am making a achievement system to save all my achievements when unlock and show which achievements is not.When I try instantiate a prefab, the z position is making my prefab look small and out of place. I need to set my position z to 0 using c# code. At the moment when I instantiate a prefab the z position value is 1557.057 and making the prefab look small in my panel.

code for instantiating the prefabs in my panel

using UnityEngine;
using System.Collections;

public class AchievementManager : MonoBehaviour {

    public GameObject achievementPrefab;

    // Use this for initialization
    void Start () 
    {
        CreateAchievement("Streak");
        CreateAchievement("Streak");
        CreateAchievement("Streak");
    }

    public void CreateAchievement(string category)
    {
        GameObject achievement = (GameObject)Instantiate(achievementPrefab);
        SetAchievementInfo(category, achievement);   
    }

    public void SetAchievementInfo(string category , GameObject achievement)
    {
        achievement.transform.SetParent(GameObject.Find(category).transform);
        achievement.transform.localScale = new Vector3(1, 1, 1);
    }
}

Answer 1

Instantiate can take position and rotation as second and third parameters respectively, so you can instantiate the object with world position and rotation of your category object like this:

GameObject achievement = (GameObject)Instantiate(
    achievementPrefab,
    GameObject.Find(category).transform.position,
    GameObject.Find(category).transform.rotation
);

Also, transform.SetParent() can take second parameter worldPositionStays, you can try setting it to false

achievement.transform.SetParent(GameObject.Find(category).transform, false);

Lastly, you can set the Z directly (the following resets only Z):

achievement.transform.localPosition = new Vector3(
    achievement.transform.localPosition.x,
    achievement.transform.localPosition.y,
    0
);