Then the ViewModel (or bloc) requests the necessary data. It shows how a developer can obtain necessary data from the server by following the shown steps: We can clearly understand what the above image illustrates. Steps in performing Network Request - Future-based Approach (Image Source: Android Developers) If the repository in the data layer returns data in the form of Stream (which the ViewModel(s) will listen to), you can consider that reactive repository.īut how is it going to help us anyway? If this is what you have been thinking, let me demonstrate two images.Ī picture is worth a thousand words - Henrik Ibsen Simply put, reactive programming is programming with asynchronous data streams. You can’t re-listen to the stream even after closing it.īroadcast Stream: This type of stream allows any number of listeners. Single-subscription Stream: This type of stream only allows one listener during the whole lifetime of that stream. Depending on the number of listeners, the stream can be categorized into two parts: The stream can be listened to by one or many listeners. Those who listen or subscribe to the stream are called subscribers or listeners. Those parts of our application that are interested in our data stream need to listen to the emitted stream, also referred to as subscribing to the stream. Stream Representation (Image By: Rajat Palankar) The data can also be modified before it is emitted. The data enters the StreamController via Sink. Similarly, the StreamController has two ends - one for letting the data come in, and the other to let it exit. If you think about it, water freely flows inside of the pipe. One for letting the water enter the pipe and the other for letting it out of the pipe. To understand it more easily, imagine a pipe that has two ends. We use it to determine what type of stream we are interested in and for some other purposes. A StreamController is basically a manager for the stream. When talking about Streams, you must also be familiar with StreamController. You will manually need to close the stream to terminate its operation. Unlike Future, when you invoke a method returning Stream, the execution doesn’t get terminated once a result is yielded (Stream’s equivalent to return). It is represented as Stream where T is any data type. Simply put, you can consider Stream as a flow of data that arrives asynchronously, meaning you don’t exactly know when a certain data is going to arrive. Table of Contentsīefore anything, let’s first talk about Streams as I already told you that it lays the foundation for reactive programming. In this article, we will learn about what streams are, when to use them, and how to use them by building a simple flutter application and bringing everything into practice. The base for reactive programming in Dart is Stream, a type in dart used to represent an asynchronous sequence of data. Import './widgets/profile_picture_widget.When it comes to reactive programming, not many developers, especially junior developers feel comfortable with it. The next step is to create the registration page view and layout the widgets: import 'package:flutter/material.dart' The goal is to replicate this design and build a fully functional registration experience. I imported all the packages I need in pubspec.yaml. Here is the current MeetUp app registration design: MeetUp Registration Page Design The exercise was designed to be a learning experience so you may have a better way to build such an app. To get familiar with Flutter, I decided to build a registration application. I copied the registration page design from the MeetUp app and built a clone in Flutter. Below is the process I used to build the app. The possibility to build Flutter apps and extend them to work on the Web with project Hummingbird, as well as native applications for desktop operating systems like Windows, Linux and Mac OS with Flutter Desktop Embedding.Robust widget libraries for iOS and Material Design.Good IDE support with Android Studio (my preferred IDE for Flutter development).Flutter seemed to solve many of the rough edges I faced when working with other mobile technologies: XAML. I started going down that path too until I saw Flutter. Many enterprise developers will feel right at home working in Xamarin because of C# and Mobile apps are fun to build. I’ve explored building apps for iOS using Objective-C and Swift and I’ve also built apps using Java for Android. While both platforms and technologies have advantages and disadvantages, it’s frustrating building the same application twice for both platforms, especially if you’re a single developer. When Microsoft acquired Xamarin I immediately saw a tremendous improvement in opportunities and tooling around Xamarin.
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