While I am developing the iOS app I need to test it in simulator with dark mode option so I can get more clarity about the app UI. But when I go to the Setting I am not getting option for dark mode as real device showing.
In Settings, scroll down to Developer and then Dark Appearance…

Alternatively, you can also switch the appearance programmatically (docs):
override func viewDidLoad() {
super.viewDidLoad()
#if DEBUG
// change the appearance only while testing
overrideUserInterfaceStyle = .dark
#endif
}
来源:https://stackoverflow.com/questions/57988687/how-to-use-dark-mode-in-simulator-ios-13