I have an Xcode project which was downloaded from the internet so I don't know which Xcode version was used to write it but the language is Swift 2. I opened it in Xcode 7.1 beta 1 and I get the following compile time error.
Failed to launch IBCocoaTouchImageCatalogTool via CoreSimulator spawn
I deleted the DerviedData foler, cleaned and build the project several times. Tried converting the project to latest Swift syntax but it says there's nothing to convert.
I'm all outta ideas. Suggestions?
The same happened to me and it was solved by cleaning the project. However, if you cleaned it —as you say you did—, I would try closing and reopening Xcode. Even though it seems stupid, it works more often than not.