Flutter - Expendable list with ExpansionTile and ExpansionPanel

In mobile application, if you want to show items in a list with expandable feature. The expandable view is a way that show items in a vertically scrolling two level list. 

 

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Android - Expandable Listview inside scrollview

In Android application, if you want to show items in a list with expandable feature. The ExpandableListView is a option that show items in a vertically scrolling two level list. It is different from the listview by allowing two level groups which can individually be expanded to show its children.

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Flutter - How to develop and distribute iOS apps without Mac

As we know, we can use Flutter framework to develop desktop, web, Android and iOS apps on window OS. But we can't run and test Flutter iOS application on window. So, whenever we develop a Flutter application on a windows machine, we always worried and a question comes 'How will this app look if we run it on an iPhone?'. As most of us know that to run the application for iOS, we need a Mac. If you don’t have Mac OS, but want to see your flutter app on an iOS device without using paid services or virtual machines then this article is for you.

In this post, I'm going to share a solution to run and test Flutter iOS app on window machine. We have an online platform Flutlab.io where we can create bundle of iOS and run this bundle on appetize.io online available simulator. Here, we going to explain complete steps to use both platforms to create bundle of iOS and run it on a simulator.

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Flutter - Icon and IconButton Examples

Flutter is a UI toolkit that used widgets for building fast, beautiful, natively compiled applications for mobile, web, and desktop. The Icon and IconButton are widgets that we can use to display a graphic representation of something, a person or thing that is symbolic.

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Flutter - Draw route on google map

The tracking feature of google map is most popular that display the current position of your ordered food and cab in a Mobile application. To implement this feature in the mobile app, we always need a google map that display the real position and path of the user.

The Google Map is a web-based service that offers the geographical regions of the world. The Google map provides aerial and satellite views of many places. The google map route planner offers directions for drivers, bikers, walkers, and users of public transportation who want to take a trip from one place to another place. You have to just enter the address of your source and destination location. After that, you will see the right way to go there. The Google maps highlight the suggested route in a bright blue color and include other possible routes in gray. It is always safe to use a driving map when you are not aware of the place.

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Flutter - Fatora payment gateway

Online money transaction is a fundamental feature of every e-commerce platform that's become a part of our daily lives. An online payment gateway is a tunnel that connects user bank account to the platform where you can transfer your money.

A payment gateway is a software that authorizes you to perform an online transaction through different payment modes like net banking, credit card, debit card, UPI, or the many online wallets that are available these days. A payment gateway plays the role of a third party that securely transfers your money from the bank account to the merchant’s payment account.

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Flutter - Quiz application by using Radio and Checkbox

In the mobile application, if you creating a feature that providing multiple options like user registration form screen where we always ask gender and hobby of the user. So, in that case, we always need a radio and checkbox widget in the application.

A Radio button used in the radio group that provides more than one radio button. The user can choose only one option at a time. A radio button has two states which are either checked or unchecked. Once a radio button is checked, it cannot be marked as unchecked by the user.

The check box is a different type of two-state button that either checked or unchecked. It is generally used in a place where user can select more than one choices from a given list of options. For example: hobby of the user or activate/deactivate the specific state.

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Flutter - Sticky header list

To divide the category of the items in the list view, we always need a sticky header. The sticky header shows header of group at the top of the list view when the user scrolls through the contents. The sticky header makes groups of children of the same type and also gives great UI.

The headers display at the top of the list content and help your application users keep track of which section they are currently in. The header may be one or more, it depends upon the type of the children items of the list view. If there is more than one header than the header will be replaced by another header when the user scrolls up all the items of the old header. 

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Flutter - Upload multipart images on server.

Sometimes, we have to upload an image on the server to complete application features like feed and user profile pic. The multipart is a simple option to upload images in the multipart request.

The Dio library also gives an option to send the multipart HTTP requests. You must use Dio
library to upload multiple file if creating a big application. The Dio client is a powerful Http client for Dart or Flutter application which supports Interceptors, Request Cancellation, Form Data, File downloading, Global configuration, Connection Timeout, etc that is explained here: Flutter - Dio client to create Http Request

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Flutter - Dio client to create Http Request

Today, all the mobile and web applications depend on back-end API's that we can consume with the help of Http client. Flutter framework offers Http package that works great when we need to do basic stuff. We have explained GET and POST request with http here Flutter - GET and POST http requests.

When you start working on a big application and we need to do something more advanced task. Your application will face lots of problems with network error handling. In that case, we need something big and advance connection library which has extra features like interceptors, logs, cache, etc, that will be helpful in many tasks like adding the token authentication for each request and logging requests.

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Flutter - Formatting TextField with TextInputFormatter

To take valid formatted data from the end-user is an essential task when your application saying to enter detail about credit cards, phone numbers, zip code, etc. This approach facilitates the developer to entering valid data in the application. It makes the process easier,  gives feedback, minimizes errors, and generally improves the user experience.

In Flutter, we can take valid formatted data with the help of TextInputFormatter widget that's provides us various different constraints. The inputFormatters property of TextFormField and TextField allows the developers to pass a list of TextInputFormatter widgets to define how that field will behave. A TextInputFormatter can be optionally inject into a TextFormField and TextField that works as a validator and correct the format of text when the text being edited. The TextInputFormatter translates the field's value into the text and the text into the field's value.

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Flutter - How to generate Android apk.

As we know, Flutter SDK can develop mobile apps for Android and iOS. So, if you have a developed Flutter application and you want to publish or distribute the Android app. You have to create a signed Android APK(Android Package Kit) file format that is used by the Android operating system. 

In this post, we going to explain how we can create a signed Flutter Android apk and publish it on google play store.

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Kotlin - Interview Questions and Answers

Kotlin is a cross-platform,  general-purpose, and statically typed programming language. Kotlin is designed to interoperate fully with Java, and the JVM version of its standard library that is depends on the Java Class Library. Here, I'm going to share the comprehensive collection of the most common and advanced Kotlin Interview Questions every Android or Kotlin developer should know.

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Flutter - Scan and Generate QR Code example

QR and Barcodes are very famous technology that widely used around us. In these codes, you can store information like text, URL, image, and a few other information.

Nowadays, most of the e-commerce companies using this technology to track their product purchase with the help of QR code and Barcode unique IDs. This QR and barcodes can only read by a physical scanner device because these are not humanly readable. 

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Flutter - Permission handler example

Our mobile contains lots of sensitive data of the users like files, financial data, contacts and other things that users can store. The mobile operating system has a privileged to keep them secure because all applications are separated from another through a distinct id. Each application work in its own process thus is isolated from all other applications. As a result, an application can’t access any file or data outside its scope until and unless the file or data is shared with the applications.
 

If an application needs anything outside its scope, then it has to request permission to the user or application. The Mobile operating system comes with a set of predefined permissions (System permissions) for certain tasks.  All mobile applications can request the required permissions to access a particular service of OS. For example, an application can declare required permissions like network, contact, and GPS.

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Flutter - Example of gradient widgets and animaion.

User-friendly interface and good color combination of the app components make a large user base for any application. The gradient is a combination of two or more colors and tints of the same color that creates great user interfaces for application. You can use gradients to create color blends, add volume to vector objects, add a light and shadow effect to the app components.

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Flutter - Web app setup with VS Code and Android Studio IDE.

As we know, Flutter is a cross-platform app development toolkit that is created by Google. It has been winning the hearts of developers and businesses across Android and iOS apps. Many renowned companies like Alibaba & Tencent have adopted it to develop native mobile apps for their production apps. Now, Google has officially added web, desktop and Embedded platforms to the world of Flutter app development. So, you can use your existing Flutter knowledge to build other platform applications. You can learn more about the new added platforms support on the official website.

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Flutter - What is Scaffold widget.

Flutter framework provides rich widgets catalogs to create a good looking material application. Here, we can see some of the key features that a material theme app must have:

• A theme for the application.
• App Bar.
• Body.
• Floating Action Button.
• Bottom Navigation Bar.

if you going to add these components to a screen with the help of separate widgets. It'll create lots of boilerplate code for one screen. This is the problem that the Scaffold Widget has resolved.

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Flutter - Interview questions

 

What is Dart?

• Dart is a client-optimized, object-oriented, class-based, garbage-collected, programming language that can be used to build mobile, desktop, server, and web applications. Dart can compile to either native code or JavaScript. It supports interfaces, abstract classes, mixins, reified generics, and type inference.

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What is Flutter?

• Flutter is a open-source mobile UI framework that is created by Google. It allows us to develop a multi platforms application with one programming language(Dart) and one code-base. It uses own high-performance rendering engine to draw widgets and systems such as animation, gesture, and widgets.

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What is the Difference between Stateless and Stateful widget?

• The Stateless widget does not require a mutable state. Stateless widgets are not dynamically changed whenever you update any value. For example, if you want to make a button or text whose title doesn't need to change dynamically, then you can create a separate widget for a button as a Stateless widget. 
• The Stateful widget has a mutable state. It means, when you want to make something that you want to change dynamically according to how a user interacts with it, then you can use the Stateful widget. For example, if you want to change the background color of the app on the click of a button, you can make use of a Stateful widget in this case.

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Flutter - Twitter Auth and Login

User authentication is a powerful feature of any application. Once an app identifies the individual users who are using the app. Then you can customize your app’s content that feels as though it was designed with a specific user in mind. 

Twitter one of the option that we can use for user authentication in applications. The Twitter API's provide login ability to the application to users. The user can easily login to the app using their twitter account which avoids filling a long sign-up form. With the help of social networks, it's much quicker and easier way of getting users signed into your app using an account they’ve already created with an external authentication provider, such as Facebook or Twitter.

We have written a post for the Facebook login feature for Flutter application:  Facebook login and authentication example.

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