Xcode 8.2 Code Completion Not Working

Update: As per @Dareon solution below also works for Xcode Version 8.3 (8E162) and 8.3.2 (8E2002). Thanks, @Dareon for the confirmation. :)

I was facing the same issue and following worked for me.

I am using Xcode Version 8.2.1 (8C1002).

1. Go to Xcode > Preferences > Text Editing
2. Under Code completion - Uncheck 'Suggest completions while typing'
3. Quit out of Xcode and then relaunch Xcode.
4. Go to Xcode > Preferences > Text Editing again
5. Quit out of Xcode and then relaunch Xcode.
6. Now go to Code completion and check 'Suggest completions while typing'.
7. Try typing library function or enum and enjoy!

At least, it worked for me.

Code completion also stopped working for me in Xcode 8.2.1, and no amount of clean-up, derived data throwaway or restart fixed it. After a while, I realized code completion was only broken within the extension scope I was working on. If typed manually, the code would be correctly highlighted and would compile fine, so it was not an issue of the source throwing off whatever parser is in charge of code completion.

Here is the specific context in which it happens, in this very simple example:

struct SomeStruct {

    static let foobar1 = {
        return NSBezierPath()
    }()

}

extension SomeStruct {

    static let foobar2 = {
        return NSBezierPath()
    }()

}

Code completion works fine within the implementation block of foobar1, but not for foobar2. It's the presence of a static let within an extension that seems to trigger it. The issue appears for both struct and class.

Looks like a bug with Xcode, so the only workaround for me was to move foobar2 into the main definition of SomeStruct.