How to debug a coroutine?

Questions & Answers
1

I’m trying to fire an IEnumerator (C#) routine from Update. I can see that the line gets there in Update, I set a break point there ok. But breakpoints in the coroutine are never hit, and nothing seems to happen. It’s like the routine is not called, and I don’t know why.

public class FrameUploader : MonoBehaviour
{
	public Texture2D texture;
	public float frameRate = 1f;
	public string prepend = "user0_";
	public int frameNum = 0;
	public bool showing = true;
	public string server = "http://myserver/uploadimage.php";
	
	float lastFrameTime = 0f;
	int q = 0;
		
	// May want to do this on physics update or late update?
	void Update ()
	{
		if ((Time.time - lastFrameTime) >= 1f/frameRate)
		{
			lastFrameTime = Time.time;
			QueueTexture(); // It gets here, if I set a breakpoint here
		}
	}
	
	IEnumerator QueueTexture()
	{
		// Cannot stop at any breakpoints here. 'q' never changes according to OnGUI
		WWW wwwToUpload = null;
		byte[] bytes = texture.EncodeToPNG();
		WWWForm form = new WWWForm();
		form.AddField("frameNum", frameNum);
		form.AddBinaryData("fileUpload", bytes, prepend+frameNum+".png", "image/png");
		wwwToUpload = new WWW (server+frameNum, form);
		q++;
		frameNum++;
	    yield return wwwToUpload;
		wwwToUpload = null;
		form = null;
		q--;
	}
	
	void OnGUI()
	{
		if (showing)
		{
			GUI.Label (new Rect (10, Screen.height-30, 200, 20), "Q: "+q);
		}
	}
}
2

You didn’t start the coroutine. You have to used StartCoroutine

    StartCoroutine( QueueTexture() );
3

QueueTexture returns an IEnumerator, and you’re ignoring that return value; that’s why nothing is happening. The coroutine is not being started.

You will need to start it with StartCoroutine(QueueTexture());

which is the same as

IEnumerator queueTextureCoroutine = QueueTexture();
StartCoroutine(queueTextureCoroutine);