Switch case with range

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.

In case that you need to check if a value is bigger than any number or between 2 values use it is possible to use where instead of if looks a bit cleaner this will work

func isOutdated(days: Int) -> Outdated {

    var outdatedStatus = Outdated.none

    switch days {
    case _ where days < 5:
        outdatedStatus = .tooLow
    case 5...10:
        outdatedStatus = .low
    case 11...20:
        outdatedStatus = .high
    case _ where days > 20:
        outdatedStatus = .expired
    default:
        outdatedStatus = .none
    }
    return outdatedStatus
}

Only for you:

enum PointsAward: Int {
    case close
    case almostBullseye
    case bullseye
}

private func calculateUserStory() -> Int {
    let bullsEyeSliderValue = 9
    let randomNumber = 100
    let diff = abs(randomNumber - Int(bullsEyeSliderValue))
    switch diff {
    case 0:
        return PointsAward.bullseye.rawValue
    case 0..<10:
        return PointsAward.almostBullseye.rawValue
    case 0..<30:
        return PointsAward.close.rawValue
    default: return 0
    }
}