Waiting for and using output of a UnityEvent within coroutines

Questions & Answers
1

I would like to wait for a UnityEvent in my coroutine AND use the output from said event in follow up execution of my code. Below is the draft code for my coroutine that waits until a card is selected by the player, triggered by an UnityEvent, and uses said card to do something (discarding / destroying / copying the card).

public IEnumerator SelectionRequest()
{
    Card card = null;

    // Wait until user has selected appropriate cards
    yield return WaitForSelection(returnValue =>
    {
        card = returnValue;
    });

    // Check if cards where selected
    if (card == null)
    {
        // Selection is aborted by user, any following code should not be executed
        yield break;
    }

    // Selection is performed correctly, 
    // Interact with the selected card in some way ...
}

The problem lies in the WaitForSelection method that i have defined, which i would like to return the Card object that was passed as input argument to a UnityEvent.

I’ve already set up a class to expose the UnityEvent for easy editing in the editor, however i have not been able to wait for the event and use this variable from within the coroutine shown above.

[System.Serializable]
public class CardEvent : UnityEvent<Card[]>
{
}

The goal of this code is to be able to implement cards with more exotic effects in my card game. From cards that allow the player to discard other cards in their hand, to cards that allow players to destroy a card in hand and select a card that costs 2 more to add to their deck.

I’m open to other suggestions if you think coroutines for the card effects, and UnityEvents for selection are not the way to go for this functionality.

2

You can use something similar to what I’ve implemented over here. Specifically a custom yield instruction that simply checks a boolean value that is set to true when the event has happened. My WaitForUIButtons class also takes care about registering and removing the callback from the button on click event. You could implement a similar class for wrapping around a UnityEvents (or multiple in case there are several choices).