How to do it...

Here, we will create the stack data structure with/without generics:

1. Create a new playground named Generics.
2. Let's create the data structure stack with type Int:

      class StackInt{ 
        var elements = [Int]() 
 
      func push(element:Int) 
      { 
        self.elements.append(element) 
      } 
      func pop() ->Int 
      { 
        return self.elements.removeLast() 
      } 
      func isEmpty()->Bool 
      { 
        returnself.elements.isEmpty 
      } 
    } 
 
    var stack1 = StackInt() 
    stack1.push(5)    // [5] 
    stack1.push(10)  //[5,10] 
    stack1.push(20) // [5,10,20] 
    stack1.pop()   // 20 

1. Let's see the same created stack but with a generics fashion:

      class Stack <T>{ 
        var elements = [T]() 
        func push(element:T) 
        { 
          self.elements.append(element) 
        } 
        func pop()->T{ 
          return self.elements.removeLast() 
        } 
      } 
 
      var stackOfStrings = Stack<String>() 
      stackOfStrings.push("str1") 
      stackOfStrings.push("str2") 
      stackOfStrings.pop() 
 
      var stackOfInt = Stack<Int>() 
      stackOfInt.push(4) 
      stackOfInt.push(7) 
      stackOfInt.pop()