Swift script for changing macos scroll bars visibility changes input sources settings

I have the following Swift script for changing scroll bars visibility in macOS:

import Foundation

func getSelectedValue() -> String {
  if CommandLine.argc < 2 {
    print("No arguments passed. Please pass one of the following values: \"Always\", \"Automatic\", \"WhenScrolling\".")
    exit(1)
  }

  let args = CommandLine.arguments
  let value = args[1]

  if value != "Always" && value != "Automatic" && value != "WhenScrolling" {
    return "Automatic"
  }

  return value
}

func setScrollBars(_ value: String) {
  let domain = "AppleShowScrollBars"

  UserDefaults.standard.setPersistentDomain(
    [domain: Optional(value) as Any],
    forName: UserDefaults.globalDomain
  )

  let notifyEvent = Notification.Name("AppleShowScrollBarsSettingChanged")
  DistributedNotificationCenter.default().post(name: notifyEvent, object: nil)
}

let value = getSelectedValue()
setScrollBars(value)

Usage example:

./set-scroll-bars Always

For some reason, running this script also causes a reset of the input source settings to their defaults:

I don’t know why it happens because I don’t see any code that is responsible for input source settings.

>Solution :

You’re updating the entire global domain to contain just one setting. All other settings in the global domain, including the input source settings, are discarded.

You need to use UserDefaults.sharedDefaults.persistentDomain(forName: UserDefaults.globalDomain) to get a dictionary containing the current settings in the global domain, and update that dictionary.

if var settings = UserDefaults.standard.persistentDomain(forName: UserDefaults.globalDomain) {
    settings["AppleShowsScrollBars"] = value
    UserDefaults.standard.setPersistentDomain(settings, forName: UserDefaults.globalDomain)
}