ionic4 cannot find module'angular-ionic'

I need to quote when writing the bullet box on the ionic4 page, but I wrote the following code but reported an error. The error is that the module'angular-ionic' cannot be found

import { AlertController } from 'ionic-angular';

This is because ionic3 is upgraded to ionic4, which is caused by the version change. The correct writing is as follows:

import { AlertController } from '@ionic/angular';