用于在C＃中使用等待方法处理事件的模式

Question

Like the subject of this post, anybody can suggest me the best way to handle an event fired with an async method in c#?

Example

// Before:
MyPosClass.EventBluetoothCommunicationCompleted+= (sender, ErrorCode) =>
            {
                // implementation on event fired
            };

// After:
var result = await MyPosClass.WaitBluetoothCommunicationCompleted();

I noticed this answer Await async with event handler Can it be a solution?

Thank you! Lewix

Answer 1

Solution of @spender seems the cleanest and it works! General purpose FromEvent method

Now my awaitable method with this improvement TaskCompletionSource throws "An attempt was made to transition a task to a final state when it had already completed" becomes:

public Task<TransactionData> PerformTransactionAwait()
{
    var tcs = new TaskCompletionSource<TransactionData>();

    EventHandler<TransactionInfo> callback = null;
    callback = (sender, TransactionDataResult) =>
    {
        MyInterface.TransactionPerformed -= callback;
        tcs.SetResult(TransactionDataResult);
    };

    MyInterface.TransactionPerformed += callback;
    MyInterface.PerformTransactionAsync();

    return tcs.Task;
}

Thank you! Lewix