WPF 一个执行耗时任务，页面更新等待时间的例子
xaml页面，一个按钮，一个lable，lable用来更新等待的时间。点击按钮，每过1秒，label的数值+1,直到任务结束。
<Window x:Class="WpfApp2.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:local="clr-namespace:WpfApp2"mc:Ignorable="d"Title="MainWindow" Height="450" Width="800"><Grid><Button Content="Button" HorizontalAlignment="Left" Margin="350,0,0,0" VerticalAlignment="Center" Height="72" Width="149" Click="Button_Click"/><Label Content="0" HorizontalAlignment="Left" Margin="350,281,0,0" VerticalAlignment="Top" x:Name="Lab"/></Grid>
</Window>
.cs代码
private async void Button_Click(object sender, RoutedEventArgs e){bool isOk = false;Wait((result)=>isOk = result);while (!isOk){//等待耗时任务结束，界面的Label加1await Task.Delay(1000);Lab.Content = Convert.ToInt32(Lab.Content) + 1;}}private async void Wait(Action<bool> callback){bool isok = false;//耗时任务for (int i = 0; i < 10; i++){await Task.Delay(1000);}isok = true;callback?.Invoke(isok);}