C# 异步任务不会继续

Question

我有个问题。在我的 Xamarin Forms 应用程序中，我使用以下代码来切换网络中的设备：

public ICommand cmdTogglePower
{
    get
    {
        return new Command<int>((x) => TogglePower_Handler(x));
    }
}

public Task TogglePower_Handler(int Id)
{
    return TogglePower(Id);
}

private async Task TogglePower(int Id)
{
    foreach (var item in knownDeviceList)
    {
        if (item.Id == Id)
        {
            if (item.State == 1) { item.State = 0; }
            else if (item.State == 0) { item.State = 1; }

            switch (item.State)
            {
                case 1:
                    item.StateShown = "Turned on";
                    item.PowerStateColor = "#FFFFFF";
                    item.DeviceImageColor = item.Color;
                    break;
                case 0:
                    item.StateShown = "Turned off";
                    item.PowerStateColor = "#707070";
                    item.DeviceImageColor = "#707070";
                    break;
            }

            foreach (var device in App.KnownDeviceList)
            {
                if (device.Id == Id)
                {
                    device.State = item.State;

                    int rgb = Convert.ToInt32(item.Color, 16);
                    int r = (rgb & 0xff0000) >> 16;
                    int g = (rgb & 0xff00) >> 8;
                    int b = (rgb & 0xff);

                    string status = await App.RestService.SendCommand(r, g, b);

                    break;
                }
            }

            break;
        }
    }
}

我希望应用程序调用 Task SendCommand，它通过网络将 https 命令发送到另一个类中的该设备。这是该任务的代码：

public async Task<string> SendCommand(int Red, int Green, int Blue)
{
    var postData = new List<KeyValuePair<string, string>>();
    postData.Add(new KeyValuePair<string, string>("red", Red.ToString()));
    postData.Add(new KeyValuePair<string, string>("green", Green.ToString()));
    postData.Add(new KeyValuePair<string, string>("blue", Blue.ToString()));

    var content = new FormUrlEncodedContent(postData);
    var weburl = "mysite.org";
    string response = await PostResponseSendCommand(weburl, content);

    return response;
}

public async Task<string> PostResponseSendCommand(string weburl, FormUrlEncodedContent content)
{
    var response = await client.PostAsync(weburl, content);
    var responseString = await response.Content.ReadAsStringAsync();

    return responseString;
}

但是代码在 int 之后停止了rgb = Convert.ToInt32(item.Color, 16); 现在任务永远不会被执行，所以有些事情出错了！

为什么这不起作用！？

Answer 1

问题：
您的颜色值以“#”开头，Convert.ToInt32()无法处理，它会导致System.FormatException: Could not find any recognizable digits. 该异常“消失”了，因为它发生在异步状态机内部。

解决方法：
砍掉前导的“#”，例如像这样：

int rgb = Convert.ToInt32(item.Color.Substring(1), 16);