Edit elements in C# after making them in XAML - xamarin

Question

I have created a couple of entries and buttons in XAML (no C# code yet).
Is it possible to edit or even add elements in C# code to a StackLayout which was made in XAML?
For example, having the following XAML code:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:ORTEC_MOBILE"
x:Class="ORTEC_MOBILE.MainPage"
BackgroundColor="#0074ff">
<RelativeLayout>
<StackLayout HorizontalOptions="FillAndExpand"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=0.25,Constant=0}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width,Factor=1,Constant=0}">
<Label Text="Login" FontSize="36" TextColor="White" HorizontalTextAlignment="Center">
</Label>
<Label Text="Welcome back! Please log into your account." FontSize="12" TextColor="White" HorizontalTextAlignment="Center">
</Label>
</StackLayout>
</RelativeLayout>
Is it possible to add a button to the layout using C# code?

Answer 1

Yes, definitely possible. When you give an element an attribute of x:Name="element" it is available in code-behind as "element". See this sample on the Xamarin site to see how they call elements in code:
https://github.com/xamarin/xamarin-forms-book-samples/tree/master/Chapter08/XamlClock
The x:Name attribute allows an object instantiated in XAML to be given a name. The rules for these names are the same as for C# variable names. Following the return of the InitializeComponent call in the constructor, the code-behind file can refer to these names to access the corresponding XAML element. The names are actually converted by the XAML parser into private fields in the generated partial class.

Answer 2

It is definately possible to add in controls programatically from the code behind, I'll give you an example below.
It's probably useful to give the component you wish to add a control to, a name, that way it can be accessed from the class behind the xaml.
So in this instance I've simply attributed a name to your xaml stack layout.
XAML:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:ORTEC_MOBILE"
x:Class="ORTEC_MOBILE.MainPage"
BackgroundColor="#0074ff">
<RelativeLayout>
<StackLayout x:Name="mainStackLayout" HorizontalOptions="FillAndExpand"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=0.25,Constant=0}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width,Factor=1,Constant=0}">
<Label Text="Login" FontSize="36" TextColor="White" HorizontalTextAlignment="Center">
</Label>
<Label Text="Welcome back! Please log into your account." FontSize="12" TextColor="White" HorizontalTextAlignment="Center">
</Label>
</StackLayout>
</RelativeLayout>
C# Backing Class:
Public void SomeMethodThatsInMyBackingClass()
{
Label newLabel = new Label {
Text = "Hello, Forms!",
FontSize = Device.GetNamedSize (NamedSize.Large, typeof(Label)),
VerticalOptions = LayoutOptions.CenterAndExpand,
HorizontalOptions = LayoutOptions.CenterAndExpand,
},
mainStackLayout.Children.Add(newLabel);
}
Using the above as a rough example should be enough for you to replicate it in your own project. Good luck.