Xamarin Forms Sketch demonstrating data binding (without strings, to nested objects, to unlimited number of fields) and common app/sketch code. Note: remove the .cs from the file name, it is only there to make GitHub format it as C#

FormsBinding.sketchcs.cs

using Xamarin.Forms;
// Additional guidance: see http://vincenth.net/blog/archive/2014/11/27/how-to-share-xamarin-forms-data-binding-code-across-xamarin-sketches-and-apps-without-using-strings.aspx 
// NOTE: Once support for creating classes is added to Xamarin Sketches,
//       there is no need for this Tuple + enum + BindName + regular expression workaround;
//       you can then simply create design data classes in the Sketch and bind to that using
//       the same syntax in both projects and sketches, e.g.:
//       SetBinding(..., (Person boundPerson) => boundPerson.Name)


// BindName helper function for use with binding to design data in Sketches.
// Usage: SetBinding(..., BindName(SomeEnum.SomeValue))
// Maps an enum property name value to a Tuple ItemX property name.
// Maps 7th and later properties to nested Tuples in Item7.
//
// Use this regular expression to convert SetBinding() code from sketch to project:
// E.g. SetBinding(..., BindName(Person.Name) will become SetBinding(..., (Person boundPerson) => boundPerson.Name
// Search:  SetBinding\s*\((?<bindableProperty>[^,]+)\s*,\s*BindName\((?<class>[^\.\)]*)\.(?<property>[^\.\)]*)\)
// Replace: SetBinding(${bindableProperty}, (${class} bound${class}) => bound${class}.${property}
//
// Use this regular expression to convert SetBinding() code from project to sketch:
// E.g. SetBinding(..., (Person boundPerson) => boundPerson.Name will become SetBinding(..., BindName(Person.Name)
// Search:  SetBinding\s*\((?<bindableProperty>[^,]+)\s*,\s*\(\s*(?<class>\w*)\s+bound\k<class>\s*\)\s*=>\s*bound\k<class>\.(?<property>\w*)
// Replace: SetBinding(${bindableProperty}, BindName(${class}.${property})
Func<Enum, string> BindName = (Enum propertyName) =>
{
    const int MaxTupleItems = 7;

    int fieldIndex = int.Parse(propertyName.ToString("D"));
    string bindName = "";
    while (fieldIndex >= MaxTupleItems)
    {
        bindName += "Item" + MaxTupleItems.ToString() + ".";
        fieldIndex -= (MaxTupleItems - 1);
    }
    bindName += "Item" + fieldIndex.ToString();
    return bindName;
};

// Names of bindable classes with properties as enum names with values for Sketch design data
// Set the first value in each enum to 1 to map to Tuple Item1
// Subsequent items will map to subsequent Tuple fields
// You can overcome the limit of 7 properties in a Tuple by making the 7th property a nested Tuple,
// which can then contain properties 7 through 12. You can keep nesting tuples to add more properties.
enum Name
{
    First = 1,
    Last
};

enum Person
{
    Image = 1,
    Name,
    Description,
    Property4,
    Property5,
    Property6,
    Property7,
    Property8,
    Property9
};

// Design data for Sketch.
// Each tuple in the list represents a Person class with a nested Name class, which is represented by a nested Tuple.
// Property7..9 are represented by a nested Tuple in Item7, demonstrating how to overcome the limit of 7 properties in a Tuple.
var persons = new List<Tuple<UriImageSource,Tuple<string, string>,string, string, string, string, Tuple<string, string, string>>> {
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1s07h2W") }, new Tuple<string, string>("Miguel", "de Icaza"), "CTO and Co-founder", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value\nNo strings, just code :-)")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1rYGvGU") }, new Tuple<string, string>("Nat", "Friedman"), "CEO and Co-founder", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value\nUse Class.Property")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://photos1.meetupstatic.com/photos/member/2/4/a/6/member_74169382.jpeg") }, new Tuple<string, string>("Vincent", "Hoogendoorn"), "Developer", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value\nCompiler checks name")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1EhFsao") }, new Tuple<string, string>("Stephanie", "Schatz"), "SVP of Sales and Customer Success", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value\nDot notate: Class.Property")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1oIYpso") }, new Tuple<string, string>("Joanne", ""), "VP of Marketing", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound field value")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/10CbVZE") }, new Tuple<string, string>("Joseph", ""), "Director of Developer Relations and Co-founder", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound field value")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1vCRbKh ") }, new Tuple<string, string>("Rob", ""), "VP of Business Development", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1rPp1vm") }, new Tuple<string, string>("Bryan", ""), "Vice President of Education Services", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value")),
    Tuple.Create(new UriImageSource { Uri = new Uri("http://bit.ly/1sXguu1") }, new Tuple<string, string>("Jason", ""), "Team Lead - Xamarin.Forms", "4", "5", "6", new Tuple<string, string, string>("7", "8", "9th bound property value")),
};

var personTemplate = new DataTemplate(() =>
{
    // Start of common App/Sketch code fragment #1 *****************************

    var image = new Image {
        WidthRequest = 100,
        HeightRequest = 100
    };
    image.SetBinding(Image.SourceProperty, BindName(Person.Image));

    var firstNameLabel = new Label();
    firstNameLabel.SetBinding(Label.BindingContextProperty, BindName(Person.Name));
    firstNameLabel.SetBinding(Label.TextProperty, BindName(Name.First));

    var lastNameLabel = new Label {
        TextColor = Color.Gray
    };
    lastNameLabel.SetBinding(Label.BindingContextProperty, BindName(Person.Name));
    lastNameLabel.SetBinding(Label.TextProperty, BindName(Name.Last));

    var titleLabel = new Label();
    titleLabel.SetBinding(Label.TextProperty, BindName(Person.Description));

    var ninthFieldLabel = new Label {
        TextColor = Color.White,
        BackgroundColor = Color.Purple
    };
    ninthFieldLabel.SetBinding(Label.TextProperty, BindName(Person.Property9));

    var nameLayout = new StackLayout {
        Children = { firstNameLabel, lastNameLabel },
        Orientation = StackOrientation.Horizontal
    };

    var textLayout = new StackLayout {
        Children = { nameLayout, titleLabel, ninthFieldLabel }
    };

    var cellLayout = new StackLayout {
        Padding = 10,
        Orientation = StackOrientation.Horizontal,
        Children = { image, textLayout }
    };

    // End of common App/Sketch code fragment #1 *******************************

    var cell = new ViewCell {
        View = cellLayout,
    };

    return cell;
});

var page = new ContentPage();

// Start of common App/Sketch code fragment #2 *****************************

var searchBar = new SearchBar { Placeholder = "Search ..." };

var listView = new ListView {
    ItemTemplate = personTemplate,
    ItemsSource = persons,
    RowHeight = 110
};

var layout = new StackLayout {
    Children = {
        searchBar,
        listView
    }
};

page.Padding = new Thickness(0, 20, 0, 0);
page.Content = layout;

// End of common App/Sketch code fragment #2 *******************************

RootPage.Children.Add(page);