c# - Xamarin Forms change text of button while wait -

i'm using xamarin forms develop cross-platform app.

i want change text of button "do something" "wait", while code processing routine, , "do something" after code finish run.

the problem is: button text change after code completed.

simple exemple:

private void button_clicked(object sender, eventargs e) {     var btn = (button)sender;     btn.text = "wait";      ...some code..      btn.text = "do something"; } 

there's way "force" update of text "wait" before code finish?

    private async void btn1_clicked(object sender, eventargs e)     {        btn1.text = "wait";          await task.run(async () =>         {             (int = 1; <= 5; i++)             {                 //if code requires ui wrap in begininvokeonmainthread                 //otherwise run code                 device.begininvokeonmainthread(() =>                 {                     btn1.text = $"wait {i}";                 });                 await task.delay(1000);             }         });          btn1.text = "done";       }