App.js

import React, { useState } from "react";
import { StatusBar } from "expo-status-bar";
import {
  StyleSheet,
  Text,
  View,
  Button,
  ScrollView,
  FlatList,
} from "react-native";
import GoalItem from "./components/GoalItem";
import GoalInput from "./components/GoalInput";

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

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

  const removeGoalHandler = (goalId) => {
    setGoalsList((currentGoals) => {
      return currentGoals.filter((goal) => goal.id !== goalId);
    });
  };

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

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

const styles = StyleSheet.create({
  screen: {
    padding: 90,
  },
});