Write this code in Swift language in xcode. NO Java or C++ code. Just swift file 

Write a program that reads in a string and passes to a function named parse(digit:) that takes a string with one character as a parameter. The function should return -1 if the input is not a digit character and the digit otherwise. Use Switch statement instead of for-in loop parse(digit: "1") // 1 parse(digit: "3") // 3 parse(digit: "a") // -1