Adding commas in to extended numbers in Swift - ios

Question

I'm wanting to add commas in to break up numbers within my iOS application.
For example:
Change 1000 into 1,000
Change 10,000 into 10,000
Change 100000 into 100,000
And so on...
What is the most efficient way of doing this, and safe-guarding against numbers post decimal point too?
So for example,
1000.50 should return 1,000.50
My numbers at the moment are Ints, Doubles and Floats - so not sure if I need to manipulate them before or after converting to Strings.
Any feedback would be appreciated.

Answer 1

The Foundation framework (which is shared between iOS and MacOS) includes the NumberFormatter class, which will do exactly what you want. You'd configure a number formatter to include a groupingSeparator. (Note that different countries use different grouping separators, so you might want to set the localizesFormat flag to allow the NumberFormatter to change the separator character based on the user's locale.
Here is some sample code that will generate strings with comma thousands separators and 2 decimal places:
let formatter = NumberFormatter()
// Set up the NumberFormatter to use a thousands separator
formatter.usesGroupingSeparator = true
formatter.groupingSize = 3
//Set it up to always display 2 decimal places.
formatter.alwaysShowsDecimalSeparator = true
formatter.minimumFractionDigits = 2
formatter.maximumFractionDigits = 2
// Now generate 10 formatted random numbers
for _ in 1...10 {
// Randomly pick the number of digits
let digits = Double(Int.random(in:1...9))
// Generate a value from 0 to that number of digits
let x = Double.random(in: 1...(pow(10, digits)))
// If the number formatter is able to output a string, log it to the console.
if let string = formatter.string(from:NSNumber(value:x)){
print(string)
}
}
Some sample output from that code:
356,295,901.77
34,727,299.01
395.08
37,185.02
87,055.35
356,112.91
886,165.06
98,334,087.81
3,978,837.62
3,178,568.97