You can connect a physical device via a USB port and it will show up in the iOS Device list for you to pick it. Then, you can deploy the app directly on your device. Note that iOS Developer membership is required for this. This method is more complex than just viewing the app via a web browser.
However, it's a must when you want to test out your code regarding device features, such as cameras or maps. If you change the code in the /src folder and want to run it again in Xcode, you have to do Ionic Cordova build ios first, because the running code is in the Staging folder of your Xcode project, as illustrated:
For debugging, ...
