Oscar Piikki
A mobile application for sending receipts to accounting. Take a picture, fill in the information about the purchase and send to accounting for approval. Available for Android and iOS.
Related article in Finnish:
Oscar Akatemiassa kehitytään oman alan ammattilaisiksi
Work
Working as a full stack developer in the development team. 3 members on the initial development, and after switching to maintenance mode, I worked on the app itself mostly alone. Others did help with the backend maintenance. Releasing the app to production was part of the job.
Technical specs
React Native application, using Expo at the beginning. The application was exported from Expo when the need for native code came.
The app communicated through own API service, written with Java and using Spring Boot.
Stack:
- React Native + JavaScript
- Java
- Swift
- Spring Boot
Notable features
Bigger features, where I was the main contributor.
AI features
Automatic image cropping / rectangle detection, using OpenCV on Android and Metal on iOS. Implemented as a native module, using JS, Java and Swift. Reasoning for this is that there was no existing implementation for our use case at the time. I learned a lot about RN native modules and image manipulation libraries.
Optical character recognition with Google ML Kit. Automatically recognize text from the receipt and try to fill in the information. Native implementations for both platforms and text parsing logic written in JavaScript. The “AI” was written mostly by experimenting with different receipts, looking at formatting and positions of elements, and positioning relative to others. So instead of machine learning I had to learn myself. I wanted to implement machine learning for this, but I lacked the expertise. The final implementation worked pretty well though for parsing the total price and place of purchase.
Firebase & Push Notifications
Push notification feature for both platforms. Native implementations for both platforms, as well as JavaScript for React Native side. Written as an external library and not directly in to the app. Application side was mostly wrapping the Firebase libraries into a native module and adding configuration. Some additional features were written to Piikki, opening a receipt’s information straight from the notification for example.
To send push notifications, Firebase integration was implemented into Oscar Cloud. This was the bigger part of this feature, and deepened my knowledge in Spring Boot and contexts.