c# - 进度条可见性被忽略

Question

我试图在启动异步任务时显示进度条，并且在异步任务完成运行后，将进度条设置回不可见。由于某种原因，progressBar 没有响应更改可见性属性的代码。

        Activity.RunOnUiThread(() =>
        {
            prog.Visibility = ViewStates.Visible;
        });

        Task<bool> createPickTask = Task.Run(() => Utils.createPick(firstBet, myBet, game));
                bool createPickResult = createPickTask.Result;

        if (createPickResult)
        {
            adapter.NotifyItemChanged(pos);
        }
        else
        {
            showErrorMessage();
        }

        Activity.RunOnUiThread(() =>
        {
            prog.Visibility = ViewStates.Gone;
        });

标签： c#asynchronousxamarin.android

Answer 1

由于某种原因，progressBar 没有响应更改可见性属性的代码。

在这部分代码全部执行之前，代码不会在 UI 上生效。您可以尝试在任务中设置进度条可见性。例如：

    private void Button_Click(object sender, System.EventArgs e)
    {
        Activity.RunOnUiThread(() =>
        {
            prog.Visibility = ViewStates.Visible;
        });

        Task<bool> createPickTask = Task.Run(/*async*/ () => {
            //await Task.Delay(3000);
            bool createPickResult = Utils.createPick(firstBet, myBet, game);

            if (createPickResult)
            {
                adapter.NotifyItemChanged(pos);
            }
            else
            {
                showErrorMessage();
            }

            Activity.RunOnUiThread(() =>
            {
                prog.Visibility = ViewStates.Gone;
            });
            return createPickResult;
        });
    }

结果是：