create a curved bottom navigation (before after implementation)

here is a demo: https://snack.expo.io/@nomi9995/cf371e

you need to use react-native-svg

yarn add react-native-svg

import React, { Component } from "react";
import {
  Text,
  StyleSheet,
  View,
  Dimensions,
  TouchableHighlight,
} from "react-native";
import Svg, { Circle, Path } from "react-native-svg";

const tabs = [1, 2, 3, 4, 5];
export default class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      pathX: "357",
      pathY: "675",
      pathA: "689",
      pathB: "706",
    };
  }
  render() {
    return (
      <View style={[styles.container]}>
        <View style={[styles.content]}>
          <View style={styles.subContent}>
            {tabs.map((_tabs, i) => {
              return (
                <TouchableHighlight
                  key={i}
                  underlayColor={"transparent"}
                  onPress={() => console.log("onPress")}
                >
                  <View>
                  </View>
                </TouchableHighlight>
              );
            })}
          </View>
          <Svg
            version="1.1"
            id="bottom-bar"
            x="0px"
            y="0px"
            width="100%"
            height="100"
            viewBox="0 0 1092 260"
            space="preserve"
          >
            <Path
              fill={"#373A50"}
              stroke={"#373A50"}
              d={`M30,60h${this.state.pathX}.3c17.2,0,31,14.4,30,31.6c-0.2,2.7-0.3,5.5-0.3,8.2c0,71.2,58.1,129.6,129.4,130c72.1,0.3,130.6-58,130.6-130c0-2.7-0.1-5.4-0.2-8.1C${this.state.pathY}.7,74.5,${this.state.pathA}.5,60,${this.state.pathB}.7,60H1062c16.6,0,30,13.4,30,30v94c0,42-34,76-76,76H76c-42,0-76-34-76-76V90C0,73.4,13.4,60,30,60z`}
            />
            <Circle
              fill={"#7EE6D2"}
              stroke={"#7EE6D2"}
              cx="546"
              cy="100"
              r="100"
            />
          </Svg>
        </View>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    overflow: "hidden",
  },
  content: {
    flexDirection: "column",
    zIndex: 0,
    width: Dimensions.get("window").width - 30,
    marginBottom: "4%",
    left: "4%",
    right: "4%",
    position: "absolute",
    bottom: "1%",
  },
  subContent: {
    flexDirection: "row",
    marginLeft: 15,
    marginRight: 15,
    marginBottom: 10,
    zIndex: 1,
    position: "absolute",
    bottom: 5,
  }
});

i hope this will help you.

Here is 2 solution according to your requirement.

If you want this type of design without selection then this code will help you : https://github.com/alex-melnyk/clipped-tabbar

And if you need on each tab selection then here is other easy library for you : https://github.com/Jm-Zion/rn-wave-bottom-bar