How Can I Return Values from Unity Coroutines After They Complete?

Unity Coroutines: Returning Values After Completion

In Unity, coroutines are commonly used for asynchronous tasks. However, they pose challenges when attempting to return values after they finish. Consider the following scenario:

Problem: A script initiates a POST request using a coroutine, but requires the return of a value when the request completes. However, the "return" statement executes before the coroutine finishes, resulting in incorrect values.

Solution: Callback via Action Delegate

1. Create an Action Delegate:

public delegate void RequestStatusCallback(int status);

2. Initiate the Request with a Callback:

In the script's Start() or Update() method, initiate the coroutine and provide the callback:

WWW www = new WWW("http://google.com");

StartCoroutine(WaitForRequest(www, (status) => {
    print(status.ToString());
}));

3. Implement the WaitForSeconds Coroutine:

private IEnumerator WaitForRequest(WWW www, RequestStatusCallback callback) {
    int tempInt = 0;
    yield return www;
    if (string.IsNullOrEmpty(www.error)) {
        if(!string.IsNullOrEmpty(www.text)) {
            tempInt = 3;
        }
        else {
            tempInt=2;
        }
    } else {
        print(www.error);
        tempInt=1;
    }
    callback(tempInt);
}

4. Use the Callback to Update Values:

The callback provides access to the status value, allowing you to update variables or perform other subsequent actions based on the request's outcome.

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