Rounding NSDecimalNumber

Question

I\'m having the hardest time figuring out something that seems like it should be very simple. I need to accurately round an NSDecimalNumber to a particular number of decimal

Answer 1

I'm using this solution:

import Foundation

extension NSDecimalNumber {
    public func round(_ decimals:Int) -> NSDecimalNumber {
        return self.rounding(accordingToBehavior:
            NSDecimalNumberHandler(roundingMode: .plain,
                                   scale: Int16(decimals),
                                   raiseOnExactness: false,
                                   raiseOnOverflow: false,
                                   raiseOnUnderflow: false,
                                   raiseOnDivideByZero: false))
    }
}

let amount = NSDecimalNumber(string: "123.456")

amount.round(2)  --> 123.46
amount.round(1)  --> 123.5
amount.round(0)  --> 123
amount.round(-1) --> 120
amount.round(-2) --> 100