Update 'README.md'

README.md

 npm install
 ionic serve -l
 ```
+
+## Usage with Xcode
+
+After installing and setting up Xcode on Mac, you can preview native versions of the apps using the emulator.
+
+```
+brew install cocoapods
+sudo xcode-select -switch /Library/Developer/CommandLineTools
+ionic capacitor run ios
+```