iOS Linting at Pinterest

Michael Schneider from Pinterest built a custom linting system that catches iOS code issues at compile time, not code review. The secret? Clang plugins that hook directly into the compiler's AST.

Pinterest's iOS team needed to enforce coding standards across a rapidly growing codebase with new engineers joining weekly. Off-the-shelf linters weren't flexible enough, so they built PINLinter using Clang's plugin infrastructure to provide instant feedback during compilation.

Key Takeaways

• Custom Clang plugin shows lint warnings directly in Xcode at compile time
• Built escape hatch using custom annotations for legitimate rule exceptions
• Created Texture-specific rules to prevent common AsyncDisplayKit performance issues
• JSON config enables different rule sets for dev versus build machines

The article reveals why they had to use a custom Clang binary instead of Xcode's built-in compiler, and the surprising workaround they needed.