Launch arguments in Swift

June 16, 2021

Xcode Swift

Launch arguments are options that are send to your app on launch.

It’s helpful in case like:

to reset data
to disable onboarding
when testing

How to set launch argument within Xcode

Select your target and select “Edit scheme…”.

Edit scheme

Then add your arguments within the “Arguments Passed on Launch” dropdown.

Edit scheme

Checking argument presence

if CommandLine.arguments.contains("-reset") {
  ...
}

UI testing

func testRemovingContact() {
  let app = XCUIApplication()
  app.launchArguments = ["-reset", "-skipOndoarding"]
  app.launch()

  ...
}

Handling arguments in a struct

struct LaunchArgumentsHandler {
  func handle() {
    resetIfNeeded()
  }

  private func resetIfNeeded() {
    guard CommandLine.arguments.contains("-reset") else {
      return
  }

  ...
}