enappd loader


Building Flutter PullToRefresh in just 15 minutes



Introduction

The pull-to-refresh pattern lets a user pull down on a list of data using touch in order to retrieve more data. The “Pull-to-refresh” gesture was first introduced by Loren Brichter in the Tweetie app and in no time it became so popular that countless apps adopted this gesture. Today “pull-to-refresh” feature is a natural part of many popular apps, including Twitter, Gmail, Tweetbot and others.

What you’ll build?

In this tutorial, you’ll build a mobile app featuring a PullToRefresh gesture using the Flutter SDK. Your app will:

  • Display a dynamic list with a random number of items
  • Each time you PullToRefresh the no of items will change in the list


That’s how our PullToRefresh gonna work

This tutorial focuses on adding a PullToRefresh gesture to a Flutter app. Non-relevant concepts and code blocks are glossed over and are provided for you to simply copy and paste.

Github Repository | @ShivamGoyal1899

Widget In Focus | RefreshIndicator


Setting up Flutter on your machine

The detailed steps to install Flutter on your personal computer & getting started with Flutter is available at the following blog

Coding the component

Component Syntax

The basic format of PullToRefresh gesture looks like the one below:

const RefreshIndicator({
Key key,
@required Widget child,
double displacement: 40.0,
@required RefreshCallback onRefresh,
Color color,
Color backgroundColor,
ScrollNotificationPredicate
notificationPredicate: defaultScrollNotificationPredicate,
String semanticsLabel,
String semanticsValue
})

Implementation

The most generic way to implement PullToRefresh is as follows:

const RefreshIndicator({
Key key,
@required this.child,
this.displacement = 40.0,
@required this.onRefresh,
this.color,
this.backgroundColor,
this.notificationPredicate = defaultScrollNotificationPredicate,
this.semanticsLabel,
this.semanticsValue,
}) : assert(child != null),
assert(onRefresh != null),
assert(notificationPredicate != null),
super(key: key);

Importing dart libraries to main.dart file

Import dart:async & dart:math libraries to your main.dart file by adding the following line at the starting of the file:

import 'dart:async';
import 'dart:math';

Putting Code in action

Amend your main.dart file as per the following code:


Building & running the application

  • Connect your Emulator or physical Android device to test the application.
  • Click on Build & Run.
  • And Boooom, your app is ready.
    The final build would look like the below illustration.


The final output of the implementation



Title
Subtitle
Kicker