How to create USER AGENT for iOS devices using swift

UserAgent.swift

import Foundation
import UIKit

//eg. Darwin/16.3.0
func DarwinVersion() -> String {
    var sysinfo = utsname()
    uname(&sysinfo)
    let dv = String(bytes: Data(bytes: &sysinfo.release, count: Int(_SYS_NAMELEN)), encoding: .ascii)!.trimmingCharacters(in: .controlCharacters)
    return "Darwin/\(dv)"
}
//eg. CFNetwork/808.3
func CFNetworkVersion() -> String {
    let dictionary = Bundle(identifier: "com.apple.CFNetwork")?.infoDictionary!
    let version = dictionary?["CFBundleShortVersionString"] as! String
    return "CFNetwork/\(version)"
}

//eg. iOS/10_1
func deviceVersion() -> String {
    let currentDevice = UIDevice.current
    return "\(currentDevice.systemName)/\(currentDevice.systemVersion)"
}
//eg. iPhone5,2
func deviceName() -> String {
    var sysinfo = utsname()
    uname(&sysinfo)
    return String(bytes: Data(bytes: &sysinfo.machine, count: Int(_SYS_NAMELEN)), encoding: .ascii)!.trimmingCharacters(in: .controlCharacters)
}
//eg. MyApp/1
func appNameAndVersion() -> String {
    guard let dictionary = Bundle.main.infoDictionary else {
        return ""
    }
    let version = dictionary["CFBundleShortVersionString"] as! String
    let name = dictionary["CFBundleName"] as! String
    return "\(name)/\(version)"
}

func UAString() -> String {
    return "\(appNameAndVersion()) \(deviceName()) \(deviceVersion()) \(CFNetworkVersion()) \(DarwinVersion())"
}

print("the UA String is as \(UAString().addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!)")