Change focus to Error pop up

Hi Guys,

I am trying to automate a sign in process of a mobile application which gives Error pop-up when invalid credentials are being entered.

While writing the script I am trying to switch the focus of the tab to the error tab so that the OK button can be clicked, but unable to do so. Can anyone help me out on changing the focus? Didn’t got any switch command for window/tab.

Thanks in anticipation!