How to calculate division remainder using modulo

Swift version: 5.0

Paul Hudson    @twostraws    May 28th 2019

Swift has a dedicated remainder operator in the form of %, and it’s used to return the remainder after dividing one number wholly into another. For example, 14 % 3 is 2, because you can fit four 3s into 14, and afterwards you have the remainder 2.

The remainder operator is helpful for calculating things like odd and even numbers – if you want alternate rows of your table to be a slightly different color, for example, you might write this:

for i in 1...10 {
    if i % 2 == 0 {
        print("Number is even")
    } else {
        print("Number is odd")
    }
}

You can also use the isMultiple(of:) method, which does more or less the same thing while being more readable:

for i in 1...10 {
    if i.isMultiple(of: 2) {
        print("Number is even")
    } else {
        print("Number is odd")
    }
}

Available from iOS 8.0

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• How to use ISO-8601 dates with JSONDecoder and Codable
• Self vs self - what's the difference?
• How to use conditional conformance in Swift
• How to convert an int to a float
• How to create an Objective-C bridging header to use code in Swift

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.