should be BindingMode.OneWayToSource — target updates source

"It must now be expended... " should read "expanded".

There are currently no issues! yay!

On the first example of GreetingsPage with BoxView (location 1978 on my eReader) the GreetingsPage constructor is closed with a square bracket "]" rather than a brace "}" .

Currently chapter 4 describes the issues arising from asynchronous I/O (such as the need for the FileHelper, etc), talks about bindings, and then goes back to I/O using tasks. Would it be possible to make the chapter more straightforward, by talking first (say) about file I/O, and then finishing off the chapter by talking about bindings? So you would not have to revisit the I/O again after already leaving the subject behind.

In fact, it might be worth splitting that chapter into two depending on how deep one wants to go into each of the two subtopics (I/O, properties).

It's an excellent text, and I have learned a lot so far. Thank you for writing it :)

Armando

Pag 29, par: "In Visual Studio, you’ll probably want to display the iOS and Android toolbars. These toolbars let you choose among emulators and devices, and allow managing the emulators. From the main menu, make sure the View > Toolbars > iOS and View > Toolbars > Xamarin.Android items are checked."

[...] View > Toolbars > Android [...]
rather than
[...] View > Toolbars > Xamarin.Android [...]

Chapter 2 page 113 in iBook.
You simplify the code from the previous page bud did not include the type. It doesn't appear to be functional without the type included.

Your code reads:
[code]
this.Padding = new Thickness (0, Device.OnPlatform (20, 0, 0), 0, 0);
[/code]

Should read:
[code]
this.Padding = new Thickness (0, Device.OnPlatform (20, 0, 0), 0, 0);
[/code]

One of the recent updates to Xamarin.Forms caused changes to ToolbarItem (e.g., Activated is now deprecated), and to Android's MainActivity (now derived from FormsApplicationActivity). This last item requires changes to the App class, which itself now derives from Application.