javascript - App and Nav in ionic2

Question

What is the difference between

this.app.getRootNav()
and this.navCtrl.push()?
In fact, the main reason is that I don’t understand the relationship and difference between the App component and Nav?

Also,
tabs does not refresh when the component switches tab. Is there any way to refresh the page when switching?
Ask for advice from the great god.

Answer 1

Second question, you can try the life cycle of NavController in the official API and add ionViewDidEnter(){}