Unity中foreach会增加GC
unity中for效率比foreach高？
在unity中使用foreach遍历集合会增加gc alloc，参考的话题：作为Unity3D的脚本而言，c#中for是否真的比foreach效率更高？
foreach造成gc alloc
Unity Mono的foreach造成GC Alloc的BUG与实测
C#遍历集合方法
ToArray
ToArray等于把Dictionary拷贝了一份
使用Linq
Enumerable.ElementAt<TSource> (IEnumerable<TSource>, Int32)
参考：https://msdn.microsoft.com/zh-cn/library/bb299233%28v=vs.110%29.aspx
方法代码
public static void Main(string[] args)
{
Dictionary<string,string> dictionary =new Dictionary<string, string>();
dictionary["engine1"] = "unity";
dictionary["engine2"] = "cocos"; //方法一
var array = dictionary.ToArray();
for (int idx = ; idx < array.Count(); idx++)
{
var itemKey = array[idx].Key;
var itemValue = array[idx].Value;
Console.Write("key:{0} ,value:{1}\n", itemKey, itemValue);
} //方法二
for (int index = ; index < dictionary.Count; index++)
{
//根据索引获取
var item = dictionary.ElementAt(index);
var itemKey = item.Key;
var itemValue = item.Value;
Console.Write("\nkey:{0} ,value:{1}\n", itemKey, itemValue);
} }
GetEnumerator(Unity推荐使用)
static void Main(string[] args)
{
Dictionary<string, string> dict = new Dictionary<string, string>();
dict.Add("C#", "4.5");
dict.Add("Java", "");
dict.Add("Python", "");
Dictionary<string, string>.Enumerator etor = dict.GetEnumerator();
while (etor.MoveNext())
{
Console.WriteLine("key = {0}, value = {1}",etor.Current.Key, etor.Current.Value);
}
}