Coroutines and Yield - Unity 4 Game Development - page 617

StartCoroutine
StartCoroutine starts a coroutine .
The execution of coroutine can be paused at any point using the yield statement. The
yield return value specifies when coroutine is resumed. Coroutines are excel-
lent when modeling behavior over several frames. Coroutines have virtually no per-
formance overhead. The StartCoroutine() function always returns a value immedi-
ately; therefore, you can yield the result. This will wait until coroutine has finished exe-
cution.
Tip
When using JavaScript, it is not necessary to use StartCoroutine ; the compiler will
do this for you. However, when writing C# code, you must call StartCoroutine . (For
more details, refer to Appendix C , Major Differences Between C# and Unity JavaScript .)
In the following example, we will show how to invoke a coroutine and continue ex-
ecuting the function in parallel:
// JavaScript user:
function Start() {
// Starting = 0.0
Debug.Log ("Starting = " + Time.time);
// StartCoroutine WaitAndPrint (In JavaScript, you can
also useWaitAndPrint(5.0) which will get the same result.
StartCoroutine(WaitAndPrint(5.0));
// Before WaitAndPrint = 5.0
Debug.Log ("Before WaitAndPrint = " + Time.time);
}
function WaitAndPrint(waitTime : float) {
//Suspend execution for 5 seconds
yield WaitForSeconds(waitTime);
// WaitAndPrint = 5.0
Debug.Log ("WaitAndPrint = " + Time.time);
}