I've been learning to program in Swift within the XCode IDE. I'm still really new to it (2 weeks). I've noticed a consistent and extremely annoying behavior of XCode that I am not able to understand and/or predictably reproduce and/or resolve. At (seemingly) random times, XCode complains that there is an invalid character in the source file. And, to "fix it", it suggests inserting a single whitespace character. I tried, just now, to type some code in XCode in an attempt to reproduce the error, but was unsuccessful. I have not been able to detect a pattern in the occurrences so as to be able to reproduce it. The offending character seems to appear near parenthesis or braces, but not always. Sometimes, it is right in the middle of a word. I looked online. I found only a small handful of articles that talk about this issue. They suggest that some keyboard shortcut is entering the offending character ... some shortcut involving "Alt". But, the thing is, I don't use any shortcuts in XCode, because I don't even know any !!! So, how could I be entering these offending characters ? Please help ! This is driving me bonkers, to the point of considering writing Swift code in Eclipse (they're writing a plugin for Swift code). Thank you !