yield and WWWForm error

I have been trying to convert the code at (the 2nd sample on the page): http://unity3d.com/support/documentation/ScriptReference/WWWForm.html

..to C# in Unity3D:

void Start () 
{   
    string dataUrl = "http://www.my-site.com/game/test.php";
    string playName = "Player 1";
    int score = -1;

    // Create a form object for sending high score data to the server
    var form = new WWWForm();
    // Assuming the perl script manages high scores for different games
    form.AddField( "game", "MyGameName" );
     // The name of the player submitting the scores
    form.AddField( "playerName", playName );
     // The score
    form.AddField( "score", score );

    // Create a download object
    WWW downloadW = new WWW( dataUrl, form );

    // Wait until the download is done
    yield return downloadW;


    if(downloadW.error == null) {
        print( "Error downloading: " + downloadW.error );
        return false;
    } else {
        // show the highscores
        Debug.Log(downloadW.text);
    }
}

I get the following error:

error CS1624: The body of rr2game.Start()' cannot be an iterator block becausevoid' is not an iterator interface type

After doing some reading I have tried changing void Start() to IEnumerator Start() ..but it says IEnumerator is is not declared..?

If I co开发者_StackOverflow社区mment out the yield command the errors go away, but of course the data doesn't load.

Please can someone help? Thank you.

---

You need to change the return type of Start(), the Start callback supports both void and IEnumerator as it's return types.

IEnumerator Start () 
{   
    string dataUrl = "http://www.my-site.com/game/test.php";
    string playName = "Player 1";
    int score = -1;

    // Create a form object for sending high score data to the server
    var form = new WWWForm();
    // Assuming the perl script manages high scores for different games
    form.AddField( "game", "MyGameName" );
     // The name of the player submitting the scores
    form.AddField( "playerName", playName );
     // The score
    form.AddField( "score", score );

    // Create a download object
    WWW downloadW = new WWW( dataUrl, form );

    // Wait until the download is done
    yield return downloadW;


    if(downloadW.error == null) {
        print( "Error downloading: " + downloadW.error );
        return false;
    } else {
        // show the highscores
        Debug.Log(downloadW.text);
    }
}

Once the return type is IEnumerator you are allowed to use the yield keyword.

Most callbacks let you return IEnumerator, some that can't are: Awake, Update, LateUpdate, FixedUpdate, OnGUI, OnEnable, OnDisable, OnDestroy. You will need to check the documentation of the event callback to see if it does not support being a co-routine.

---

yield can not be used in the Start() function, it needs to be called within its own thread, instead try this:

void Start()
{
    StartCoroutine(SaveScore());
}

IEnumerator SaveScore() 
{   
    string dataUrl = "http://www.my-site.com/game/test.php";
    string playName = "Player 1";
    int score = -1;

    // Create a form object for sending high score data to the server
    var form = new WWWForm();
    // Assuming the perl script manages high scores for different games
    form.AddField( "game", "MyGameName" );
     // The name of the player submitting the scores
    form.AddField( "playerName", playName );
     // The score
    form.AddField( "score", score );

    // Create a download object
    WWW downloadW = new WWW( dataUrl, form );

    // Wait until the download is done
    yield return downloadW;


    if(!string.IsNullOrEmpty(downloadW.error)) {
        print( "Error downloading: " + downloadW.error );
    } else {
        // show the highscores
        Debug.Log(downloadW.text);
    }
}