you can use Async - native C# functionality, it is nothing to do with Unity however it is depends on the Unity main thread, and if you try to execute Unity Thread depending stuff (for example: WWW or WWWForm) you will get error. However even than could be ignored and manually implemented through native C# WebClient class
it is slightly complex and require use of C# delegates, also actual class where you going to implement async routine shouldn’t extend MonoDeveloper class
here is example:
Lets say we create simple C# script and attach it to the Main Camera
MyAsyncExecutor.cs - Class to attache to Main Camera
public class MyAsyncExecutor: MonoBehaviour {
// Use this for initialization
void Start () {
AsyncController ac = new AsyncController();
ac.StartAsyncCalculation();
}
// Update is called once per frame
void Update () {
}
}
Create AsyncController.cs class NOTE: dont extend MonoDeveloper
public class AsyncController {
//int is async return type //arguments
private delegate int AsyncCalculatorDelegator(int dig1, int dig2);
public void StartAsyncCalculation()
{
// Create delegate and define what it going to do
//in this example it will call "int AsyncCalculator.Calculate(int, int)"
AsyncCalculatorDelegator myDelegate = new AsyncCalculatorDelegator(new AsyncCalculator.Calculate);
int dig1 = 10;
int dig2 = 20;
//Now Execute it asynchronously by passing arguments and defining event response method
myDelegate.BeginInvoke(dig1, dig2, new AsyncCallback(CalculationResponse), null);
}
public void CalculationResponse(IAsyncResult result)
{
//lazy recast
AsyncResult res = (AsyncResult)result;
//getting delegate back
AsyncCalculatorDelegator myDelegate = (AsyncCalculatorDelegator)res.AsyncDelegate;
//getting actual result from async calculation
int sumResult = myDelegate.EndInvoke(result);
//now you can do with sumResult whatever you want as it was calculated Async-ly
}
}
Finally create class where you will do actual calculation: AsyncCalculator.cs
public class AsyncCalculator {
public int Calculate(int dig1, int dig2)
{
//do your calculations here
//and return result as declared type
//in this case it should be int
int sum = dig1 + dig2;
return sum;
}
}
here you are 
you did sum calculation in async way
There are new features in .Net 4.5 with use of “async” “Task” and “await” it is much easier to use it, however im not sure yet how Unity will handle it, as Unity create by default C# project in .Net 3.5 and “Task” is not available in 3.5
as you see there are 4 other ways of implementing parallel calculations which I found so far, they are:
- “StartCorutine”, “IEnumereble” and “yield” - native Unity thing
- “Delegates”, “BeginEnvoke” and “EndEnvoke” - example I showed
- “Task” and “await” = new thing in .Net 4.5
- “Threads” - never look at it yet in C#
