Fresh Beginning

currency exchange

How Currency Exchange Rates Affect Import and Export

Currency exchange rate changes have far greater implications than remittence. I came to know about this fact recently while reading Naked Economics. Based on whether currency is weak or strong, country may gain more profits with either exports or imports. To get started, let's consider very trivial example from this

inflation

Effect of inflation on lending

Recently, I came across interesting economic phenomenon when inflation hits the economy. Usually when you lend someone money, you expect to get the exact amount back plus any interest. This is acceptable under regular circumstances, but when inflation hits, the purchasing power of money greatly reduces and if such money

JSON

Using Codable Protocol in iOS to Decode Complex JSON Objects

A while back, I wrote a blog post about using Codable to encode/decode JSON payload while sending to or receiving from the server. However, I often find myself in situations where having straightforward examples with a single complex JSON is easier to understand how I can use it for

iOS

[iOS][Swift] Adding timer on reusable UITableViewCells

A few months ago I started the job search and in my very first take-home assignment, I was asked to implement a feature to display timer on UITableViewCell. The use-case was we were going to fetch Bitcoin prices every 60 seconds and the cell would display how long it is

UITableView

Best practices for configuring the table view cells on iOS with Swift

Many times, iOS developers utilize UITableView and UITableViewCell subclasses and sometimes UICollectionView variants to create beautiful views. But it could be tricky when you're writing it for the first time. It's important to know the best practices on how to configure these cells. In this post, I am going to

Async

Async / Await in Swift

Apple introduced the concept of async/await in Swift 5.5 and announced it in WWDC21 session. Today, we are going to see it in action and how you can leverage it to write readable async code in your app. Please note that async/await is only available in Swift

ARC

Deep dive into Swift memory management with ARC

It's been a while since my last post. For past few months I was busy with work, personal life and lot of things happening outside it so couldn't really commit to writing another article. However, I am back now and going to write about Swift and its memory management quirks.

Algorithm

[Algorithm Question] Finding the origin of a Computer Virus from the given list of machine pairs

Recently, I worked on the algorithm problem that required to find the origin of computer virus given the list of infected machine pairs. In general you're given the input in the form of computer pairs (a, b) which indicates the virus infection from machine a to machine b. The goal

NSNotifications

Implementing custom NotificationCenter in Swift

NSNotificationCenter is a classic API on iOS. It's used so that classes can register for notifications by name and execute the function/block whenever the notification with same name is fired somewhere else in the project. Today, we will see how to implement NSNotificationCenter API in Swift from scratch. Here

Xcode 12 Beta

Value of type UICollectionViewListCell has no member leadingSwipeActionsConfiguration / trailingSwipeActionsConfiguration

Apple introduced new APIs to add leading and trailing swipe configuration in Xcode 12 Beta. They were introduced in Lists in UICollectionView video at 11:38 mark. However, needless to say, they're no longer valid and that's the whole reason why this blog post. Back in July when I was

Potato

Making a Homemade French-fries

Being in a lockdown for more than 6 months is stressful. However, it doesn't have to be like that all the time. Couple of weeks back I was feeling rather low-energy and depressed. I didn't know what I should do to get rid of this feeling. Then I remembered I

Xcode 12

TableView via CollectionView on iOS - Lists in UICollectionView

🛑 Read Before ProceedingPlease make sure that you are using Xcode 12 (Beta or stable release) and above supporting iOS 14 and later versions. Most of the APIs mentioned in this post were announced during WWDC-2020 and shipped with iOS 14. If you don't have Xcode 12 or later, you can

iOS

iOS - Creating Programmatic Layout without using Storyboard (Swift/Objective-C)

There are two ways of creating layout on iOS. First, using readymade storyboard provided by Xcode when you create a new project. And second, by manually creating a UIViewController subclass and assigning it to UIWindow object as a rootViewController in AppDelegate class. However, things have changed since Xcode 11 and

ComponentKit

Creating a Facebook Timeline using ComponentKit

In the past few days I have taken a special interest in learning ComponentKit framework. From the official GitHub page, it's a React-inspired view framework built for the iOS. ComponentKit is written in Objective-C++. Although those ++ look scary, the library hides all the complexities associated with both Objective-C and C+

hooks

Playing with React Hooks - Async operation with Loading state

Recently I started learning React.js. While the framework has so many fascinating features, the particular one I liked is Hooks. Although hooks is relatively new feature and isn't widely used yet, I tried to learn it with more hand-on approach by making a demo app comprising of loading state,

quick-select

Implementing Quick Select Algorithm - Finding kth largest/smallest element

Today I am going to write about a special type of algorithm for finding a kth largest or smallest element in the array. This is my favorite data structure question due to intricacy involved in solving the problem. There are many variants of this problem including more efficient using max/

Indian Food

Making a Methi Vadi (A snack made of Fenugreek Leaves)

When I was a kid, Methi vadi was one of my favorite snacks. Although I liked it, I never learned how to make it from my mom. As I grew up and started cooking at home by myself, I got cravings for eating Methi vadi and since none of the

tic-tac-toe

Algorithm to Detect A tic tac toe Winner

Recently I was asked to work on the game of tic tac toe on iOS. Creating a game layout and rest of the business logic is straightforward, until it comes to detecting whether either side has won the game or not. There are 2 ways of solving this problem -

image downloader

Using ImageDownloader library with reusable cells

This is the second part of original post where I wrote about how I built an image downloader and caching library for images. (webp and gif excluding). However, there is one thing which was briefly mentioned but wasn't elaborated is how to use this library with reusable cells. As we

Swift 4.0

Architecting Asynchronous Image Download and Caching in Swift

Few months ago, I worked on a side-project that involved writing image downloader and cacher from scratch without using a third-party library. Today, in this blog post I am going to summarize how I built this framework from scratch with details technical explanation. Before I started working on the project,

Coronavirus

Making a Coronavirus Prevention Mask - A new side project

With the spread of Coronavirus, everyone is rushing to buy masks. I too unsuccessfully tried to buy masks online, but couldn't get one due to high demand. Whenever Amazon showed me the availability of masks, the delivery became a problem. Even though some businesses were selling masks, those wouldn't have

iOS

Drag and Drop on iOS using Swift

Hello folks, it's been a while since I wrote my last article. Today we're going to learn how to implement drag and drop feature on iOS using Swift. To see in advance what we're going to achieve by the end of this tutorial, please watch the following video, To summarize

UICollectionView

Tutorial - Creating Programmatic UICollectionView in Swift

Creating a UICollectionView could be stressful - As compared to dealing with UITableView. But things don't have to be this way for so long. Every time I have to add a CollectionView in the app, I end up spending long time trying to figure out what did I do last

memory semantics

Swift Value and Reference type semantics - Structs, Classes, Struct inside Class, Class inside Struct

Long ago Swift introduced a nice concept differentiating between value and reference semantic using Struct and Classes. As we all know, Struct is a value semantic, which means when value of one struct is assigned to another struct, only value is copied, not the reference - Which in other words

Codable

Codable - Applying Data Transformations

Codable may not just all be blindly transforming JSON data into model objects, but you can also apply formatting to it. Examples of formatters include, but not limited to date formatters, URLs, and fractional data types. In this post we're going to take a look at some of those formatters