生成不同类型的对象

从你的描述和评论听起来像是你想要保证在speiclaCratePercentageMin和speiclaCratePercentageMax之间的板条箱百分比是特殊创建，但其余的可以只是普通创建。如果是这样的话，你所需要做的就是计算出这个百分比将占总数的多少个箱子，首先刷出这个百分比，然后用正常的箱子填充其余的箱子。

using UnityEngine;
using System.Collections.Generic;
using UnityEngine.UI;
public class spawnmanager : MonoBehaviour {
public int noOfobjects = 6;
public Transform[] spawnPoints;  
public GameObject normalCrate;
public GameObject specialCrate;
public float speiclaCratePercentageMin;
public float speiclaCratePercentageMax;
void Awake()
{
}
// Use this for initialization
void Start () 
{
    spawner();
}
void spawner ()
{
    List<Transform> availablePoints = new List<Transform>(spawnPoints);
    //Figures out how many special creates we need.
    int numberOfSpecialCrates = noOfobjects * Random.Range(this.speiclaCratePercentageMin, this.speiclaCratePercentageMax);
    //Added i<spawnPoints.Length check to prevent errors when noOfobjects is bigger than the number of available spawn points.
    for (int i = 0; i<noOfobjects && i<spawnPoints.Length;i++)
    {    
        int spawnPointIndex = Random.Range (0, availablePoints.Count);
        //As long as i is lower than numberOfSpecialCrates we spawn a special crate.
        if(i < numberOfSpecialCrates)
        {
            Debug.Log("dd");
            Instantiate(specialCrate, availablePoints[spawnPointIndex].position, Quaternion.identity);
        } 
        else
        {
            Instantiate(normalCrate, availablePoints[spawnPointIndex].position, Quaternion.identity) ;
        }     
        availablePoints.RemoveAt(spawnPointIndex);
    }
}
}

我认为问题在这里if (randomFloat>=1 || randomFloat <=0.9f &&randomFloat>= 0.7f)

最好使用更多括号

if (randomFloat>=1 || (randomFloat <=0.9f &&

看看这个问题。