Switch case with range

Question

I'm learning Swift and tried to program the game "Bullseye" from Ryan Wenderlich by my own before watching the videos.

I needed to give the user points depending on how close to the target number he was. I tried to calculate the difference and than check the range and give the user the points, This is what I did with If-else (Couldn't do it with switch case):

private func calculateUserScore() -> Int {
    let diff = abs(randomNumber - Int(bullsEyeSlider.value))
    if diff == 0 {
        return PointsAward.bullseye.rawValue
    } else if diff < 10 {
        return PointsAward.almostBullseye.rawValue
    } else if diff < 30 {
        return PointsAward.close.rawValue
    }
    return 0 // User is not getting points. 
}

Is there a way to do it more elegantly or with Switch-Case? I couldn't just do diff == 0 for example in the case in switch case as xCode give me an error message.

Answer 1

This should work.

private func calculateUserScore() -> Int {
    let diff = abs(randomNumber - Int(bullsEyeSlider.value))
    switch diff {
    case 0:
        return PointsAward.bullseye.rawValue
    case 1..<10:
        return PointsAward.almostBullseye.rawValue
    case 10..<30:
        return PointsAward.close.rawValue
    default:
        return 0
    }
}

It's there in the The Swift Programming Language book under Control Flow -> Interval Matching.