How to start pip mode when switching in recent apps

I used this example code to show pip window when the app will go to background,but i find this no used be on recent app switch. and the enterPictureInPictureMode() will return false. everyone can help me to slove this problem ,thx

@Override
public void onUserLeaveHint () {
    if (iWantToBeInPipModeNow()) {
        enterPictureInPictureMode();
    }
}

I want to app on recent app switch that can go to pip mode