There is a bug in the Swift compiler / indexer. Some line or lines in your code is giving it difficulty. You will have to edit your code with some other text editor to comment out the offending line(s) before you will be able to open that project with Xcode. If you have no clue what the problem is, comment out all your code. Once you have the project open, you can start bringing back code little by little until the rise in CPU activity tells you that you've found the problem.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…