compile times in Swift

Why are compile times so slow?

• Why Swift’s type checker is so slow ・ Daniel Hooper
• https://www.cocoawithlove.com/blog/2016/07/12/type-checker-issues.html

Workarounds

You may have expressions in your code slowing down compile times. To find the worst offenders, run:

xcodebuild clean build -project <YOUR PROJECT FILE NAME>.xcodeproj/ OTHER_SWIFT_FLAGS="-Xfrontend -debug-time-expression-type-checking" | grep -Ei '^\d+\.\d+ms\t/.+$' | sort -r

Use temporary variables to break the slow expressions into multiple statements. In addition, it might be worth adding -Xfrontend and -warn-long-expression-type-checking=100 to your project’s “Other swift flags” build setting to be warned when an expression takes longer than 100 milliseconds to compile.

• From: Why Swift’s type checker is so slow ・ Daniel Hooper