One super power that the switch statement possesses, is its ability to match values to an expression that exist within intervals. An interval denotes a range used for checking whether a given value lies within that range.

In Swift, a range is indicated by three consecutive dots, ..., also known as the closed range operator. The closed range operator signifies an inclusive range where the first and last values are included in the sequence.

Let’s see these new concepts in action. In the example below, the switch statement determines the value of year and checks which century it belongs to.

var year = 1943

switch year {
  case 1701...1800:
    print("18th century") 
  case 1801...1900:
    print("19th century")
  case 1901...2000: 
    print("20th century")
  case 2001...2100: 
    print("21st century")
  default: 
    print("You're a time traveler!")
} 
// Prints: 20th century

Since the year, 1943, falls between the interval, 1901...2000, the code for the third case is executed and the message, 20th century gets printed.

Fun fact: The first electronic computer was built in 1943! 💻