Design Patterns:

In this project, I try to implement common design pattern with some understandable examples:

Factory Design Pattern:

Method Factory: we use this pattern when we need to manage creating objects and we don't care about child class(or subclass) type. Imagine we need a cross platform printer class which writes a text to console. So we have interface like:

public interface IPrinter
{
   void Print(string text);
}

For Windows and Linux we implement class like this:

public class LinuxPrinter : IPrinter
{
    public void Print(string text)
    {
        Console.WriteLine($"Linux Printed: {text}");
    }
}
public class WindowsPrinter : IPrinter
{
        public void Print(string text)
        {
            Console.WriteLine($"Windows Printed: {text}");
        }
}

In the client class we don't care about of type of the class that is LinuxPrinter or WindowsPrinter and we just want to print. So it's a good idea to use Method Factory Design Pattern and we create the following class:

public class PrinterFactory
{
    public static IPrinter Create(OsType type)
    {
       switch (type)
       {
          case OsType.Linux:
               return new LinuxPrinter();
          case OsType.Windows:
               return new WindowsPrinter();
          default:
               throw new ArgumentException("Type Not found!");
      }
   }
}
public enum OsType
{
   Linux,
   Windows
} 

As you see the create method just return an IPrinter interface:

var printer = PrinterFactory.Create(OsType.Windows);

printer.Print("This printer test");

Abstract Factory: This design pattern extend method factory in the other word it's a factory of factories. Sample Code:

 public class GenericUIFactory
 {
        public static IUIComponent Create(OSUIType os,ComponentType component)
        {
            IUIFactory uiFactory;
            switch (os)
            {
                case OSUIType.Android:
                    uiFactory=new AndroidFactory();
                    break;
                case OSUIType.IOS:
                    uiFactory=new IOSFactory();
                    break;
                default:
                    throw new ArgumentException("Os Not Found!");
                    
            }
            return uiFactory.Create(component);
        }
 }
 public enum OSUIType
 {
   Android,
   IOS
 }

In the code above at first we create a factory class based the selected OS after that we create a IUIComponent by the factory that we've created before.

var Button=GenericUIFactory.Create(OSUIType.IOS,ComponentType.Button);
Button.Render();