If something goes wrong or the simple Clean and rebuild does not work, you must delete the contents of these folders right now (carefully).
~/Library/Developer/Xcode/DerivedData ~/Library/Developer/Xcode/Archives ~/Library/Developer/Xcode/iOS DeviceSupport ~/Library/Developer/CoreSimulator ~/Library/Caches/com.apple.dt.Xcode ~/Library/Application Support/MobileSync/Backup
![](https://1.bp.blogspot.com/-R1MMSKzMQoE/Xs0Qemj_tvI/AAAAAAAACsk/1q56NfmkWO8RU5nMoO1PHLrf47AFTI1ZgCK4BGAsYHg/s1200/How%2Bto%2Bdelete%2Bcache%2Band%2Bfree%2Bspace%2Bon%2BXcode.png)
Thanks to the source.