Updated for Xcode 12.0
If you have existing paths made using UIBezierPath
or CGPath
it’s trivial to convert them for use in SwiftUI because the Path
struct has an initializer directly from CGPath
.
Note: UIBezierPath
is not available in macOS, so if you’re trying to keep your SwiftUI code cross platform you should migrate to CGPath
instead.
As an example, here’s a UIBezierPath
extension I made to store the logo for an app I built, called Unwrap:
extension UIBezierPath {
/// The Unwrap logo as a Bezier path.
static var logo: UIBezierPath {
let path = UIBezierPath()
path.move(to: CGPoint(x: 0.534, y: 0.5816))
path.addCurve(to: CGPoint(x: 0.1877, y: 0.088), controlPoint1: CGPoint(x: 0.534, y: 0.5816), controlPoint2: CGPoint(x: 0.2529, y: 0.4205))
path.addCurve(to: CGPoint(x: 0.9728, y: 0.8259), controlPoint1: CGPoint(x: 0.4922, y: 0.4949), controlPoint2: CGPoint(x: 1.0968, y: 0.4148))
path.addCurve(to: CGPoint(x: 0.0397, y: 0.5431), controlPoint1: CGPoint(x: 0.7118, y: 0.5248), controlPoint2: CGPoint(x: 0.3329, y: 0.7442))
path.addCurve(to: CGPoint(x: 0.6211, y: 0.0279), controlPoint1: CGPoint(x: 0.508, y: 1.1956), controlPoint2: CGPoint(x: 1.3042, y: 0.5345))
path.addCurve(to: CGPoint(x: 0.6904, y: 0.3615), controlPoint1: CGPoint(x: 0.7282, y: 0.2481), controlPoint2: CGPoint(x: 0.6904, y: 0.3615))
return path
}
}
That uses control points that are normalized to the range of 0 through 1, so that I can render it inside any kind of container and just scale it up to fit the available space.
In SwiftUI that would mean creating a transform that scales the Bezier path up by the minimum of either the width or the height, then applying that to a path, like this:
struct ScaledBezier: Shape {
let bezierPath: UIBezierPath
func path(in rect: CGRect) -> Path {
let path = Path(bezierPath.cgPath)
// Figure out how much bigger we need to make our path in order for it to fill the available space without clipping.
let multiplier = min(rect.width, rect.height)
// Create an affine transform that uses the multiplier for both dimensions equally.
let transform = CGAffineTransform(scaleX: multiplier, y: multiplier)
// Apply that scale and send back the result.
return path.applying(transform)
}
}
With all that in place, we can now render any kind of Bezier path we want:
struct ContentView: View {
var body: some View {
ScaledBezier(bezierPath: .logo)
.stroke(lineWidth: 2)
.frame(width: 200, height: 200)
}
}
If you’re starting with a CGPath
rather than a UIBezierPath
, things are even easier. This line:
let path = Path(bezierPath.cgPath)
Becomes this:
let path = Path(yourCGPath)
SPONSORED From January 26th to 31st you can join a FREE crash course for iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a senior developer!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Link copied to your pasteboard.