Swift Fallthrough语句

switch(expression){
   case constant-expression :
      statement(s);
      break; /* optional */
   case constant-expression :
      statement(s);
      break; /* optional */

   /* you can have any number of case statements */
   default : /* Optional */
      statement(s);
}

switch expression {
   case expression1 :
      statement(s)
      fallthrough /* optional */
   case expression2, expression3 :
      statement(s)
      fallthrough /* optional */

   default : /* Optional */
      statement(s);
}

var index = 10

switch index {
   case 100 :
      print( "Value of index is 100")
   case 10,15 :
      print( "Value of index is either 10 or 15")
   case 5 :
      print( "Value of index is 5")
   default :
      print( "default case")
}

Value of index is either 10 or 15

var index = 10

switch index {
   case 100 :
      print( "Value of index is 100")
      fallthrough
   case 10,15 :
      print( "Value of index is either 10 or 15")
      fallthrough
   case 5 :
      print( "Value of index is 5")
   default :
      print( "default case")
}

Value of index is either 10 or 15
Value of index is 5