App.js

import React from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View
} from 'react-native';


import Tabs from './src';

export default class App extends Component{
  state = {
    cities: [] 
  }
  addCity = (city) =>{
    const cities = this.state.cities
    cities.push(city)
    this.setState({cities})
  }

  addLocation = (location, city) => {
    const index = this.state.cities.findIndex(item => {
      return item.id === city.id
    })
    const chosenCity = this.state.cities[index]
    chosenCity.location.push(location)
    const cities = [
      ...this.state.cities.slice(0, index), 
      chosenCity,
      ...this.state.cities.slice(index + 1)
    ]
    this.setState({
      cities
    })
  }

  render(){
    return(
      <Tabs
        screenProps={{
          cities: this.state.cities, 
          addCity: this.addCity,
          addLocation: this.addLocation
        }}
        />
    )
  }
}