NEW! Master Swift design patterns with my latest book! >>

How to create a QR code

Paul Hudson       @twostraws

iOS has a built-in QR code generator, but it's a bit tricksy to use because it's exposed as a Core Image filter that needs various settings to be applied. Also, it generates codes where every bit is just one pixel across, which looks terrible if you try to stretch it inside an image view.

So, here's a simple function that wraps up QR code generation while also scaling up the QR code so it's a respectable size:

func generateQRCode(from string: String) -> UIImage? {
    let data = string.data(using: String.Encoding.ascii)

    if let filter = CIFilter(name: "CIQRCodeGenerator") {
        filter.setValue(data, forKey: "inputMessage")
        let transform = CGAffineTransform(scaleX: 3, y: 3)

        if let output = filter.outputImage?.transformed(by: transform) {
            return UIImage(ciImage: output)
        }
    }

    return nil
}

let image = generateQRCode(from: "Hacking with Swift is the best iOS coding tutorial I've ever read!")

Available from iOS 7.0

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

Other people are reading…

About the Swift Knowledge Base

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

Upgrade to premium

The Hacking with Swift guide book helps you learn faster, plus get an Xcode tips and tricks video and Swift wall chart.

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Average rating: 5.0/5

Click here to visit the Hacking with Swift store >>