Issue Description:

I am attempting to use CTFont code, and wrote this code:

private func localizedNameForFontFamily(_ family: String) -> String
 {
 let font = CTFontCreateWithName(family as CFString, 0.0, nil) return CTFontCopyLocalizedName(font, kCTFontFamilyNameKey, nil) ?? family 
 }

which spawned this error: "CFString is not impicitly convertable to String, did you mean to use as to explicitly convert"

Following this advice gives us this code:

private func localizedNameForFontFamily(_ family: String) -> String
{
    let font = CTFontCreateWithName(family as CFString, 0.0, nil) return CTFontCopyLocalizedName(font, kCTFontFamilyNameKey, nil) as String ?? family 
} 

which then prompted the error "CFString? is not convertable to String, did you mean to use as! to force downcast?" which seems incorrect, since the actual issue is that we need to cast to `String?`, (adding the optional).

additionally, if you go with that suggestion again:

private func localizedNameForFontFamily(_ family: String) -> String
{
    let font = CTFontCreateWithName(family as CFString, 0.0, nil) return CTFontCopyLocalizedName(font, kCTFontFamilyNameKey, nil) as! String ?? family 
}

you get the warning "Forced cast from `CFString?` to `String` only unwraps and bridges, did you mean to use ! with as?"

which is particularly frustrating as it seems to be suggesting that we return to the code that was originally written!

the successfully compiling code here is:

private func localizedNameForFontFamily(_ family: String) -> String
{
    let font = CTFontCreateWithName(family as CFString, 0.0, nil) return CTFontCopyLocalizedName(font, kCTFontFamilyNameKey, nil) as String? ?? family 
} 

I would expect that at some point in this cycle the suggestion would be to cast to an optional String, rather than adjusting the type of casting that is happening.