WWDC23 SALE: Save 50% on all my Swift books and bundles! >>

How to draw a circle using Core Graphics: addEllipse(in:)

Swift version: 5.6

Paul Hudson    @twostraws   

Core Graphics is able to draw circles and ellipses with just a few lines of code, although there is some set up to do first. The example code below creates a 512x512 circle with a red fill and a black border:

let renderer = UIGraphicsImageRenderer(size: CGSize(width: 512, height: 512))
let img = renderer.image { ctx in
    ctx.cgContext.setFillColor(UIColor.red.cgColor)
    ctx.cgContext.setStrokeColor(UIColor.green.cgColor)
    ctx.cgContext.setLineWidth(10)

    let rectangle = CGRect(x: 0, y: 0, width: 512, height: 512)
    ctx.cgContext.addEllipse(in: rectangle)
    ctx.cgContext.drawPath(using: .fillStroke)
}

Please note: although a 10-point border is specified, Core Graphics draws borders half-way inside and half-way outside the path you create, so if you want to see the whole border (rather than have it cropped) you either need to draw a smaller shape or create a bigger context.

Save 50% in my WWDC23 sale.

SAVE 50% To celebrate WWDC23, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.

Save 50% on all our books and bundles!

Available from iOS 4.0 – see Hacking with Swift tutorial 27

Similar solutions…

About the Swift Knowledge Base

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

BUY OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.8/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.