Coroutines and Yield - Unity 4 Game Development - page 608

Coroutines
StartCoroutine returns a Coroutine . Instances of this class are only used to refer-
ence these coroutines and do not hold any exposed properties or functions.
A coroutine is a function that can suspend its yield execution until the given
YieldInstruction class finishes calling.
An example of coroutine is as follows:
// JavaScript user:
function Start() {
// Starting = 0.0
Debug.Log ("Starting = " + Time.time);
// Start function WaitAndPrint as a Coroutine
yield WaitAndPrint();
// Done WaitAndPrint = 5.0
Debug.Log ("Done WaitAndPrint = " + Time.time);
}
function WaitAndPrint() {
//Suspend execution for 5 seconds
yield WaitForSeconds(5);
// WaitAndPrint = 5.0
Debug.Log ("WaitAndPrint = " + Time.time);
}
// C# user:
IEnumerator Start() {
// Starting = 0.0
Debug.Log ("Starting = " + Time.time);
// Start function WaitAndPrint as a Coroutine
yield return WaitAndPrint();
// Done WaitAndPrint = 5.0
Debug.Log ("Done WaitAndPrint = " + Time.time);