How to check for NSDecimalNumber.zero() in Swift

Question

Using 'num1' as a comparison reference to determine if 'num2' or 'num3' are zero. Have done this successfully in Objective-C, and am trying to do it in Swift:

let num1: NSDecimalNumber = NSDecimalNumber.zero()
let num2: NSDecimalNumber = NSDecimalNumber.decimalNumberWithString("0")
let num3: NSDecimalNumber = NSDecimalNumber.decimalNumberWithString("0.000001")

if num1.compare(num2) == NSOrderedSame {
    println("They match")
}

This attempt results in: "error: use of unresolved identifier 'NSOrderedSame'." What is the proper way to accomplish this in Swift? (Have searched the book and web, but missing something possibly obvious, thank you).

Anchises

Answer 1

Do you mean: num1.compare(num2) == NSComparisonResult.OrderedSame

Polychromy

Yes! Thank you, that's exactly what I was looking for. Now to learn how to find that myself in the apple documentation : ) – Anchises

Swift can infer the NSComparisonResult so you can drop it (still need the .) – Thomas

Answer 2

in Swift that can happen an easier way, like e.g. this:

    if num1 == num2 {
        println("They match")
    }

BACKGROUND

(extracted from Using Swift Cocoa and Objective-C APIs, Object Comparison section)

Swift and Objective-C objects are typically compared in Swift using the == and === operators. Swift provides a default implementation of the == operator for objects that derive from the NSObject class. In the implementation of this operator, Swift invokes the isEqual: method defined on the NSObject class.

Bolshevism

Are you sure this is true about NSNumber objects? – Guelph

I could not find the reference currently (I will) but the Swift automatically converts those == opreators to an -isEqual: method for Obj-C objects, like e.g. NSNumbers. – Bolshevism

I'm trying to find it again... to be fair, in the last two weeks I've been reading all possible documentation of Swift and I have no idea where I found it... but I will find it again, because that would be a very useful information. – Bolshevism

According to my test, it appears to work, will look for the reference also. (I haven't tested for the cases of NSOrderAscending and NSOrderDescending though). – Anchises

@LeoNatan, I found the reference again, and I've added to my answer. – Bolshevism

@H_H, I've attached the reference. :) – Bolshevism

@LeoNatan, Thank you! I should try the <, >, <=, and >= comparisons too, they might work just as well. – Anchises

Answer 3

If you're working with NSDecimalNumber often, I'll plug my own operator overloads here: https://gist.github.com/anisoptera/5708afc32454ed868363

Takes care of that irritating unclear "NSOrdered..." comparison and even lets you do such crazy things as add two NSDecimalNumbers with the + operator!

Lymphocyte