Xamarin. Простые элементы UI Xamarin Forms

Кнопка - Button

	var Button = new Button {
	Text = "Click Me!"
	};

view raw Button.cs hosted with ❤ by GitHub

Поле ввода - Entry

	var numEntry = new Entry {
	Placeholder = "Enter Number",
	Keyboard = Keyboard.Numeric
	};

view raw Entry.cs hosted with ❤ by GitHub

Пример обработчика для поля ввода

	var numEntry = new Entry {...};
	numEntry.TextChanged += OnTextChanged;
	...
	void OnTextChanged(object sender, string newValue){
	...
	}

view raw Entry.cs hosted with ❤ by GitHub

Больше элементов UI в официальной документации (на английском)