How to truncate decimals to x places in Swift

Question

In my swift program, I have a really long decimal number (say 17.9384693864596069567) and I want to truncate the decimal to a few decimal places (so I want the

Answer 1

I figured this one out.

Just floor (round down) the number, with some fancy tricks.

let x = 1.23556789
let y = Double(floor(10000*x)/10000) // leaves on first four decimal places
let z = Double(floor(1000*x)/1000) // leaves on first three decimal places
print(y) // 1.2355
print(z) // 1.235

So, multiply by 1 and the number of 0s being the decimal places you want, floor that, and divide it by what you multiplied it by. And voila.