Convert numbers to and from strings in Swift

Convert numbers to and from strings in Swift

// To convert a number to a string
var costString = String(9.99)
// To convert a string to an Int
var wholeNumber = Int("27")
// To convert a string to an Float
let lessPrecisePI = Float("3.14")
// To convert a string to an Double
let morePrecisePI = Double("3.1415926536")