App.js

import { StatusBar } from "expo-status-bar";
import React, { useState } from "react";
import { StyleSheet, View, Button, FlatList } from "react-native";

import GoalItem from "./components/GoalItem";
import GoalInput from "./components/GoalInput";

export default function App() {
  const [courseGoals, setCourseGoals] = useState([]);
  const [isAddMode, setIsAddMode] = useState(false);

  const addGoalHandler = (goalTitle) => {
    setCourseGoals((currentGoals) => [
      ...currentGoals,
      { key: Math.random().toString(), value: goalTitle },
    ]);
    setIsAddMode(false);
  };

  const deleteGoalHandler = (goalId) => {
    setCourseGoals((currentGoals) => {
      return currentGoals.filter((goal) => goal.key !== goalId);
    });
  };

  const cancelGoalHandler = () => {
    setIsAddMode(false);
  };

  return (
    <View style={styles.screen}>
      <Button title="Add new Goal" onPress={() => setIsAddMode(true)} />
      <GoalInput
        visible={isAddMode}
        onAddGoal={addGoalHandler}
        onCancel={cancelGoalHandler}
      />
      <FlatList
        data={courseGoals}
        renderItem={(itemData) => (
          <GoalItem
            title={itemData.item.value}
            onDelete={deleteGoalHandler.bind(this, itemData.item.key)}
          />
        )}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  screen: {
    padding: 50,
  },
});