Is there any way to know a component is on screen in ReactNative? like viewDidAppear or viewWillAppear

Question

If you're writing Swift you can use ViewController's life cycle hook, viewDidAppear or viewWillAppear to know whether specific View is on screen. Is there any way to do the similar thing in ReactNative? looks like no close one in the docs

Answer 1

I don't think react native provides any functions which are called when you pop to previous view(unlike methods like componentWillMount() which is called when component mounts).

But I think you can pass a callback function when you navigate to new scene, and just before popping it call this function.

When you push a new component 'B' from 'A'

In Component A

callBackPop() {

 // manipulate state
}

pushNewScene() {
  this.props.navigator.push({name: 'B', callBack: this.callBackPop});
}

In Navigator

renderScene(route, navigator) {

  <B navigator={navigator} callback={route.callBack} />

}

In Component B

function popToPrevious() {
     this.props.callBack();

     this.props.navigator.pop();

}