Swift NSAttributedStringKey not applying foreground color correctly

Use negative strokeWidth if you'll set foregroundColor as well. Otherwise, only the stroke is seen.

let attributes = [
        NSAttributedStringKey.strokeColor.rawValue: UIColor.black,
        NSAttributedStringKey.backgroundColor.rawValue: UIColor.red,
        NSAttributedStringKey.foregroundColor.rawValue: UIColor.white,
        NSAttributedStringKey.font.rawValue: UIFont(name: "HelveticaNeue-CondensedBlack", size: 40)!,
        NSAttributedStringKey.strokeWidth.rawValue: -4.5]

Swift 5

let attributes = [
        NSAttributedString.Key.strokeColor: UIColor.black,
        NSAttributedString.Key.backgroundColor: UIColor.red,
        NSAttributedString.Key.foregroundColor: UIColor.white,
        NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-CondensedBlack", size: 40)!,
        NSAttributedString.Key.strokeWidth: -3.0]

Edit: See rmaddy's comment about why we need the rawValue in this case below.

Stroke width responsible for this, Negative stroke value can solve your problem.

Swift 4.2

let attributes = [
        NSAttributedString.Key.strokeColor.rawValue: UIColor.black,
        NSAttributedString.Key.backgroundColor.rawValue: UIColor.red,
        NSAttributedString.Key.foregroundColor.rawValue: UIColor.white,
        NSAttributedString.Key.font.rawValue: UIFont(name: "HelveticaNeue-CondensedBlack", size: 40)!,
        NSAttributedString.Key.strokeWidth.rawValue: -3.0]

Swift 5

let attributes = [
        NSAttributedString.Key.strokeColor: UIColor.black,
        NSAttributedString.Key.backgroundColor: UIColor.red,
        NSAttributedString.Key.foregroundColor: UIColor.white,
        NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-CondensedBlack", size: 40)!,
        NSAttributedString.Key.strokeWidth: -3.0]