MergeSwiftModule - Building a Swift app in Xcode 6.3 gets stuck in "Merge MyApp.swiftmodule"

Question

Building an app in Xcode 6.3 gets stuck for several minutes (approx. 10mins) on a step Merge MyApp.swiftmodule:

MergeSwiftModule normal x86_64 /Users/.../Library/Developer/Xcode/DerivedData/MyApp-crbdsfrhkvpiynaffvhzzsspiels/Build/Intermediates/MyApp.build/Debug-iphonesimulator/MyApp.build/Objects-normal/x86_64/MyApp.swiftmodule

this wasn't an issue in previous version of Xcode 6.2 and Swift 1.0.

Titrate

Delete 'Derived Data', 'Reset your Simulator' and 'Clean Project'. These are the most common things and will solve your problem too. – Faenza

That unfortunately doesn't help. – Titrate

Answer 1

Enabling SWIFT_WHOLE_MODULE_OPTIMIZATION for the target seems to fix this issue.

Source: https://devforums.apple.com/message/1119343#1119343

Titrate

Option can be found under "Swift Compiler - Code Generation" on the Build Settings tab of your target. Thanks so much for sharing the fix! – Nightshirt