FileSize struct with Double extension

FileSize.swift

import Foundation
// 

struct FileSize {
    enum Unit: Int {
        case b = 0, kb, mb, gb, tb, pb, eb, zb, yb
    }
    var bytes: Int = 0
    init(_ bytes: Int) {
        self.bytes = bytes
    }
    func human(as unit: Unit) -> String {
        let suffixes = ["B", "K", "M", "G", "T", "P", "E", "Z", "Y"]
        let exp = unit.rawValue
        let suffix = suffixes[exp]
        let val = Double(bytes) / pow(1024.0, Double(exp))
        
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        formatter.maximumFractionDigits = 1
        let formattedValue = formatter.string(from: NSNumber(value: val)) ?? "0"
        return "\(formattedValue)\(suffix)"
    }
    subscript(unit: Unit) -> Double {
        (Double(bytes) / pow(1024.0, Double(unit.rawValue)))
    }
}
extension Double {
    var b:  FileSize { return FileSize(Int(self               ))}
    var bytes: FileSize { b }
    var kb: FileSize { return FileSize(Int(self * pow(1024, 1)))}
    var kilobytes: FileSize { kb }
    var mb: FileSize { return FileSize(Int(self * pow(1024, 2)))}
    var megabytes: FileSize { mb }
    var gb: FileSize { return FileSize(Int(self * pow(1024, 3)))}
    var gigabytes: FileSize { gb }
    var tb: FileSize { return FileSize(Int(self * pow(1024, 4)))}
    var terabytes: FileSize { tb }
    var pb: FileSize { return FileSize(Int(self * pow(1024, 5)))}
    var petabytes: FileSize { pb }
    var eb: FileSize { return FileSize(Int(self * pow(1024, 6)))}
    var exobytes: FileSize { eb }
    var zb: FileSize { return FileSize(Int(self * pow(1024, 7)))}
    var zettabytes: FileSize { zb }
    var yb: FileSize { return FileSize(Int(self * pow(1024, 8)))}
    var yottabytes: FileSize { yb }
}


2.gb.human(as: .mb)
64087267.b.human(as: .mb)
1504.21.petabytes.human(as: .mb)

1.tb[.mb]