Demonstrate working example in NavigationView

[devraj]

Reported Issues:

• In a secondary pushed in view the app crashes

When prototyped in the app:

• The model was updating but the cell first responder won't change cells
• Navigating manually changes the cell index
• Arbitrarily navigating between cells resets the index to 1

[devraj]

From initial investigation the problem appears to be due to the Model object