Happy Numbers

Write an algorithm to determine if a number n is "happy".

A happy number is a number defined by the following process: 
Starting with any positive integer, replace the number by the sum of the squares of its digits, 
and repeat the process until the number equals 1 (where it will stay), 
or it loops endlessly in a cycle which does not include 1. 
Those numbers for which this process ends in 1 are happy numbers.

Return True if n is a happy number, and False if not.

Example: 

Input: 19
Output: true
Explanation: 
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

func isHappy(_ n: Int) -> Bool {
        
    }