The switch control out of the Xamarin.Forms toolbox does not appear to be MVVM compliant. That means that its toggle (as a result of a UI tap) changes the state of the switch w/o validating or asking the Model (via the ViewModel) if it should change its state. I tried handling a "toggling" event or subclassing the switch but was unable to find a OOP solution to this problem. Instead I disabled the control and handled the ItemSelected event on the listView which first validates and then changes the state of the IsToggledProperty binding property. The disadvantage of incorrectly using the IsEnabled property is dimming an otherwise active control but at this point I'm able to live w/ this downside.
I switched my start page from a NavigationPage to a TabbedPage and all of a sudden the content overwrote the the carrier/battery row. I looked into this and discovered that the TabbedPage does not offset itself below this header in iOS (but works for android and windows). The solution is to add a platform dependent offset or padding thickness of 20 pixels.