Xcode 9 stuck on Swift 4 migration

Question

I am trying to migrate my Swift 3 project to Swift 4 in Xcode 9. After selecting a target and selecting output options @obcj Xcode is permanently stuck on a Generating previewspinning wheel. How can I transfer my project?

Answer 1

In the same conversion dialog box, clear the check box Remind meand click Convert Later. Now go to Build Settingsand change Swift Language Versionto Swift 4.0. Most likely, this will cause a lot of warnings or errors. Unfortunately, you have to fix them manually.