Screen life cycle events
Understanding screen onStart and onEnd
Whenever a screen is mounted and unmounted, there are two methods gets called for each screen.
onStart:
This method is called whenever screen is mounted.
const screen = {
    name: 'WelcomeScreen',
    screen: {
    v1: [text, ...],
    },
    onStart:({setUi, getUi })=>{
        // do something on screen mounted
    }
};
onEnd:
This method is called whenever screen is unmounted
const screen = {
    name: 'WelcomeScreen',
    screen: {
    v1: [text, ...],
    },
    onEnd:({setUi, getUi })=>{
        // do something on screen unmounted
    }
};