NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to draw a square using Core Graphics: addRect()

Swift version: 5.2

Paul Hudson    @twostraws   

You can draw a square (or indeed any size of rectangle) using the addRect() Core Graphics function. There's a little bit of set up work required, such as creating a context big enough to hold the square and setting up colors, but the code below does everything you need:

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.addRect(rectangle)
    ctx.cgContext.drawPath(using: .fillStroke)
}

Important note: when setting a line width using setLineWidth(), the center of the border is the edge of your path. This means our board will be 5 points inside the rectangle and 5 points outside, because we have a total border width of 10 points. Because the square's path is the same size as the context, this means the outside part of the border will be clipped.

Subscribe to Hacking with Swift+

Sponsor Hacking with Swift and reach the world's largest Swift community!

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 Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) 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 Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.5/5

Link copied to your pasteboard.