Samuel Edwin

A React Native chat app that is used by the community and managed by the client.

The client didn't have someone who was an expert at React Native before I joined. This makes the project way behind schedule, and the app contains many unresolved bugs. Once I joined the team, I quickly learned how the codebase works and solved longstanding bugs in just a few hours. I also helped the team complete the feature development so the app could be launched with minimal bugs and complaints.

The Indonesian Government's Procurement Platform is going through a digital transformation.

The project involved building multiple apps, including:
• Purchasing platform for all government ministries.
• Seller platform for businesses selling their products.
• Internal tools for admins.

I was in charge of the technical aspects of all front-end applications. That included development, testing, and deployment.

Here are some of my contributions:
• Performed code reviews and gave feedback to pull requests.
• Hired and interviewed candidates.
• Built and documented best practices for front-end developers in the team.
• Worked with back-end developers to develop a GraphQL schema that is easy for developers to use.
• Built CI/CD environment for quick application deployment.

Led this project on the technical side to improve the UI and the UX of existing Tokopedia's home screen.

You can see the complexity of the feature in the video:
• Lots of different widgets are displayed on one screen.
• A sticky tab bar (0:11 in the video) that needed special care to implement.
• Pinterest-like layout at the bottom of the list.
• Needs to be smooth on iPhone 5, the oldest iPhone we support.

This was almost impossible to implement, especially the sticky tab bar. Nobody knew how to implement this at that time. I managed to find an elegant implementation by reverse engineering Instagram, which used the same UI pattern.

The previous iteration had many widgets, and the code was a mess to maintain. This iteration has many more widgets, but I managed to find a code structure that makes these widgets easy to maintain. Maintaining this feature is fun now, unlike before.

To make it smooth on iPhone 5, I learned new tricks from the iOS community to optimize UI performance. Scrolling on iPhone 5 now feels butter smooth. I achieved the Pinterest-like layout by applying my extensive knowledge of the iOS UI system.

Tokopedia has lots of UI designers working on multiple products. They don't frequently communicate, resulting in inconsistent UI behavior. This is a huge waste of time because engineers need to build the same UI components repeatedly.

The engineering team and the UI design team solved this problem by creating a reusable component library.

Here are my contributions to this project:
• Talking to UI designers whenever something was impossible to implement and offering alternative solutions that work just as well.
• Brainstorming with engineers on how to implement tricky components.
• Building some of the UI components.
• Reviewing the components' API to make them easy to use.

This resulted in a huge productivity boost both for the engineers and the UI designers. Engineers didn't have to waste time rebuilding the same components anymore, and UI designers didn't have to reinvent new ones. They can now simply pick a UI element from the catalog and plug it into Figma.

I led this rewrite project with one team member. This rewrite was necessary because of a few reasons:
• Thousands of lines in one file, very hard to understand.
• Crashes frequently.
• Lots of bugs.
• Slow performance.

Here's what I did to solve these problems:
• Developed a coding pattern that makes it easy to maintain a large number of different widgets.
• Used Swift's language features to make crashes almost impossible to happen.
• Reduced the amount of code written significantly by adopting a framework called IGListKit.
• Adopted a new UI framework to make the performance smooth.

The Tokopedia app contains dozens of different products. The app supports eCommerce activities, paying monthly bills, booking flights, social commerce, and much more. This means the codebase is huge, which takes a lot of time to build. It can take 30 minutes to build a project, wasting a lot of engineers' time.

I led this project along with two engineers with one main goal—to improve the engineers' productivity by improving build speed.

I did two things here; the first one is splitting the code into multiple modules, ensuring that rebuilds only happen for the code that we change. To make this happen, I learned the inner workings of the Xcode build system to learn why rebuilds happen. The second one is adopting Bazel as our build system. Using Bazel's cache, we can shave off more time to build our app. We now only need to spend around two minutes for our app to build successfully.

At Tokopedia, we use a lot of back-end services in the app. It is often hard to know when something went wrong with the back-end side.

I contributed to this project by talking to engineers and their managers to define such problems. I prioritized solving the issues in the order of their occurrence rate.

Here are some issues we often encounter:
• Images often don't load under specific internet providers.
• Some features suddenly don't work because of a back-end deployment that went wrong.
• Wrong deep link URLs stop the users from navigating to a particular screen.

We then used New Relic to log all the problems described above. We built dashboards and alerts to be notified immediately when something went wrong, so the troubleshooting time goes way faster. This makes our engineers feel safe because whatever problems that show up, they have the tools to solve them.

A tvOS app that provides entertainment through streaming TV shows similar to Netflix.
I translate the design from Figma into a usable app used by end-users.

One particularly challenging part of the project is managing the focus for remote controls, which I learned a lot from this project.

Technologies used:
• SwiftUI
• Combine
• Composable Architecture (Redux)

This is a feature that lets users book Uber from the Tokopedia app.
It also has a similar flow to the original Uber app:
• Select pick up and destination
• Select the type of vehicle
• Wait until the user is picked up
• Go with the driver until the user safely arrives at the destination

We use React Native for this feature to speed up development time.

Challenge one: Feature complexity
There are lots of edge cases in this feature. We use Redux to manage the states.

Challenge two: Native code integration
We are integrating this React Native feature to an existing native app.
We wrote a bridge so the JavaScript layer could reuse the native authentication code.
We use Airbnb's deprecated React Native Navigation to navigate between native and React Native screens.

An effort to create a TypeScript infrastructure library that is used by the iOS and Android team.

The library covers the most common use cases that product engineers need:

• Networking
• Authentication
• Navigation
• Deeplinking
• Push notification

The most important thing in this project was the API design. The APIs we designed had to work on iOS and Android and be easy for product engineers to use.