3. Simulators

iOS

Get a list of available simualtors:

$ xcrun simctl list | grep iPhone\ 8
iPhone 8 (7DE38F7F-E661-4819-94CC-4E4888EE8DC4) (Shutdown)
...

Choose a simulator and boot:

$ xcrun simctl boot 7DE38F7F-E661-4819-94CC-4E4888EE8DC4

Open the simulator app:

$ open -a simulator

Android

List available emulators:

$ emulator -list-avds
Pixel_API_26

Launch an emulator:

$ cd $(dirname $(which emulator)) && ./emulator -avd Pixel_API_26 -dns-server 8.8.8.8

Note:- -dns-server 8.8.8.8 specifies the default DNS, you might be able to omit this depending on you machines network configuration. See emulator command-line docs