Shaving off 50% waiting time from the iOS Edit-Build-Test cycle
Article Summary
A Spotify engineer cut iOS build times in half during a mobile bootcamp. Here's how two simple settings changes saved 10 minutes per developer, per day.
When a developer with no iOS experience joined Spotify's mobile bootcamp, the 82-second Edit-Build-Test cycle became unbearable. Instead of accepting it, they profiled the build process and found two major bottlenecks eating 62% of wait time.
Key Takeaways
- Switch to plain DWARF debug format instead of dSYM for dev builds
- Avoid -O4 optimization flag which triggers costly Link Time Optimizations
- dSYM generation took 25 seconds but isn't needed during development
- Static library with -O4 made linking 51% slower than necessary
- Changes save 10 minutes per developer daily with zero tradeoffs
Critical Insight
Two XCode build settings reduced iOS Edit-Build-Test cycles by 50%, saving 40 seconds per iteration without compromising debug capabilities.
