Haptico pattern with duration parser

Pattern.swift

import Foundation 

class Impact {
    private let duration: Int
    init(with string: String) {
        let result = string.replacingOccurrences( of:"[Oo.()]{1,}", with: "", options: .regularExpression)
        self.duration = Int(result)!
    }

    var description: String {
        return "Duration: \(self.duration)"
    }
}
class BigImpact: Impact {
}
class MediumImpact: Impact {
}
class SmallImpact: Impact {
}

class ImpactFactory {
    static func impact(for string: String) -> Impact {
        let startIndex = string.startIndex
        let substring = string[startIndex]
        switch substring {
        case "O":
            return BigImpact(with: string)
        case "o":
            return MediumImpact(with: string)
        case ".":
            return SmallImpact(with: string)
        default:
            print("Error occured: \(substring)")
            return Impact(with: "")
        }
    }
}

let pattern = "O(4)o(4)"

let string = "O(4)o(4).(18).(180)"
let regex = try! NSRegularExpression(pattern: "((O|o|.){1})([(]{1})([0-9]{1,3})([)]{1})")
let range = NSRange(string.startIndex..., in: string)
let results = regex.matches(in: string, options: .anchored, range: range)
    .map { match -> Substring in
        let range = Range(match.range(at: 0), in: string)!
        return string[range]
    }

let impacts: [Impact] = results.map { substring in
    guard let substring = substring as? Substring else { return BigImpact(with: "") }
    let string = String(substring)
    return ImpactFactory.impact(for: string)
}

impacts.forEach { print($0.description) }
print(impacts)