What is Cocoa touch class ?

Answer 1

These are premade classes to specifically handle views, pickers, and other such things for iOS apps. When you make a new Cocoa Touch class for something, you select what element it's for, and the class automatically inherits from existing Cocoa Touch classes and generates some methods it may need.
Ex: A Cocoa Touch class for a normal view would look a bit like this:

import UIKit //This allows interaction with the UI elements (labels, buttons, etc.)

class ViewController : UIView //This class is for a UIView
{
override func viewDidLoad()
{ super.viewDidLoad(); }

//and some other functions
}