sYn
A short-video social app where creators earn crypto for the views they pull.
Sole iOS engineer (freelance) · Freelance engagement · Shipped
Overview
sYn is a TikTok-style vertical video feed with one twist: creators are paid in crypto based on the views their videos collect. I built the iOS app end to end as the sole mobile engineer on the project.
Problem
Short-video platforms monetize creators late and opaquely — payout programs are gated, thresholds are high, and the relationship between views and earnings is invisible. sYn's premise was to make the loop direct: views convert to coin earnings a creator can watch accrue in real time.
Solution
A full-screen, gesture-driven feed built for the watch-loop — instant start, seamless swipes — paired with an in-app wallet where earnings per video are first-class UI, not a buried statistics page.
Upload, playback, engagement and payout flows all live in the one app, backed by the platform's API for view accounting and coin settlement.
Architecture
MVVM with a player pipeline as the heart of the app: a small pool of reusable AVPlayer instances, aggressive pre-buffering of the next items in the feed, and strict teardown to keep memory flat during long sessions.
Paginated feed loading with prefetch windows tuned so a swipe almost never meets a spinner, plus push-driven updates for earnings events.
Engineering challenges
Smooth infinite video on mid-range devices
The feed had to feel instant on hardware far below flagship iPhones. That meant profiling player reuse, capping concurrent decodes, and prefetching just enough — too little buffering shows spinners, too much evicts what the user is watching.
Money must never be approximate
Crypto balances mix tiny per-view increments with large precision requirements. All amounts stayed in exact decimal/string representations from API to UI — floating point never touched a balance — with display rounding as a pure presentation concern.
Lessons learned
- Video feeds are a resource-management problem wearing a UI costume — the architecture that matters is the player lifecycle, not the view hierarchy.
- When money is on screen, correctness beats cleverness everywhere it competes with it.
Tech stack
- Swift
- UIKit
- AVFoundation
- MVVM
- REST APIs
- Push notifications