Adding missing parts
First, let's run the app for the first time to see where we are.
The app starts with a blank screen with just one plus (+) button in the upper-right corner.
So, there is work to do here. But, let's move on and tap the plus (+) button. We are presented with the input view. We can add data for the item and tap the Save button.
But, when we tap the Save button, nothing happens. Dismiss the view by swiping down, and see whether the item was added. Something changed. There is a blank table view cell visible in the middle of the screen.
When you tap the blank table view cell, the detail view is pushed onto the screen.