You can toggle the interface mode (i.e. Light / Dark) as well as adjust dynamic type setting on the fly (when the simulator is running) like this:

You can use the "Toggle Appearance" (ShiftCommandA) setting from the Simulator menu:

Simulator > Features > Toggle Appearance ⇧⌘A

Automated Appearance Change 🦉

Xcode 11.4 🌟

Apple released a powerful Xcode update which contains some useful things for this topic. Appearance can now be selected directly in the simulator. Just select Features > Toggle Appearance or ⇧+⌘+A. The automatic appearance switching could stil be important, e.g. for automated screenshot tests on the command line. The script becomes easy like this when using Xcode 11.4:

device_ids=("C741F3CD-FDAC-49EA-A4DB-7F797B97291E" "428183B6-3EB8-4D36-9938-9D07C141BF49") # The value to use is now just 'dark' or 'light' appearance=dark for device in "${device_ids[@]}"; do xcrun simctl boot $device xcrun simctl ui $device appearance $appearance done 

No more simulator killing or re-setting needed which is a huge performance win. Also no fiddling around with any plist tools anymore - ever. keep in mind that you have to use device ids that are available in the runtime you use. Find them out using xcrun simctl list.

See also my complete script: https://github.com/Blackjacx/Scripts/blob/master/set-simulator-style.sh

Xcode 11.3

There is a way using the command line to switch a simulator between light and dark mode. If you have an array with your device IDs you can do the following:

device_ids=("C741F3CD-FDAC-49EA-A4DB-7F797B97291E" "428183B6-3EB8-4D36-9938-9D07C141BF49") # Determine the plist value for the desired style: "dark" -> 2 / "light" -> 1 style=2 for device_id in "${device_ids[@]}"; do plist_path="${HOME}/Library/Developer/CoreSimulator/Devices/${device_id}/data/Library/Preferences/com.apple.uikitservices.userInterfaceStyleMode.plist" printf '\n%s' "Set style $style for device $device_id ($plist_path)" killall "Simulator" xcrun simctl shutdown booted xcrun simctl erase $device_id # Crate the plist since it might not be available after erase [[ ! -f "$plist_path" ]] && /usr/libexec/PlistBuddy -c "save" $plist_path # Set the style mode plutil -replace UserInterfaceStyleMode -integer $style $plist_path done 

If you want to specify device names in your script - since device IDs are different on different machines - you can also easily find the id's of them using the following bash code:

device_names=("iPhone SE" "iPhone 8" "iPhone 11 Pro" "iPhone 11 Pro Max") device_ids=() for name in "${device_names[@]}"; do id=$(xcrun simctl list --json | jq ".devices | .[] | .[] | select(.name == \"$name\") | .udid" | cut -d\" -f2) device_ids+=("$id") done printf '%s\n' "${device_ids[@]}" 

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 } 

from terminal:

xcrun simctl ui booted appearance light xcrun simctl ui booted appearance dark 

There are two ways to enable dark mode in Simulator. Note: Make sure that you’re using iOS 13 simulator. X-D

Solution 1: Change build settings

1. Open Settings app
2. Select Developer
3. Enable Dark appearance

Solution 2: Programmatically

Simply add this code block in your ViewController file.

override func viewDidLoad() { super.viewDidLoad() #if DEBUG // This changes appearance only for debug mode overrideUserInterfaceStyle = .dark #endif } 

Check this apple docs for more details.

How to switch between Light, Dark, and Tinted appearances in the Xcode Simulator (iOS 18+)

If you're looking to test your app icon or UI under different system appearances in the Xcode Simulator, here's how to toggle between modes. This is especially useful when checking how your app icons or assets behave in Light, Dark, or the new Tinted mode (iOS 18 only):

Steps:

1. Long press on an empty space on the Home Screen or on any App Icon.

2. Tap the Edit button in the top-left corner (occasionally appears top-right depending on Simulator version).

3. Tap Customize.

4. Choose between Light, Dark, Automatic, or Tinted.

📝 Note: Tinted mode is only available starting in iOS 18.

I know it's not exactly what the author asked, but if you're using SwiftUI you can check how a View looks in Light or Dark themes directly in the Preview canvas, as shown in the image: