Utilise the private CoreSVG framework in Swift

SVG.swift

import Darwin
import Foundation
import UIKit

// https://github.com/xybp888/iOS-SDKs/blob/master/iPhoneOS17.1.sdk/System/Library/PrivateFrameworks/CoreSVG.framework/CoreSVG.tbd
// https://developer.limneos.net/index.php?ios=17.1&framework=UIKitCore.framework&header=UIImage.h

@objc
class CGSVGDocument: NSObject { }

var CGSVGDocumentRetain: (@convention(c) (CGSVGDocument?) -> Unmanaged<CGSVGDocument>?) = load("CGSVGDocumentRetain")
var CGSVGDocumentRelease: (@convention(c) (CGSVGDocument?) -> Void) = load("CGSVGDocumentRelease")
var CGSVGDocumentCreateFromData: (@convention(c) (CFData?, CFDictionary?) -> Unmanaged<CGSVGDocument>?) = load("CGSVGDocumentCreateFromData")
var CGContextDrawSVGDocument: (@convention(c) (CGContext?, CGSVGDocument?) -> Void) = load("CGContextDrawSVGDocument")
var CGSVGDocumentGetCanvasSize: (@convention(c) (CGSVGDocument?) -> CGSize) = load("CGSVGDocumentGetCanvasSize")

typealias ImageWithCGSVGDocument = @convention(c) (AnyObject, Selector, CGSVGDocument) -> UIImage
var ImageWithCGSVGDocumentSEL: Selector = NSSelectorFromString("_imageWithCGSVGDocument:")

let CoreSVG = dlopen("/System/Library/PrivateFrameworks/CoreSVG.framework/CoreSVG", RTLD_NOW)

func load<T>(_ name: String) -> T {
    unsafeBitCast(dlsym(CoreSVG, name), to: T.self)
}

public class SVG {
    
    deinit { CGSVGDocumentRelease(document) }
    
    let document: CGSVGDocument

    public convenience init?(_ value: String) {
        guard let data = value.data(using: .utf8) else { return nil }
        self.init(data)
    }
    
    public init?(_ data: Data) {
        guard let document = CGSVGDocumentCreateFromData(data as CFData, nil)?.takeUnretainedValue() else { return nil }
        guard CGSVGDocumentGetCanvasSize(document) != .zero else { return nil }
        self.document = document
    }
    
    public var size: CGSize {
        CGSVGDocumentGetCanvasSize(document)
    }
    
    public func image() -> UIImage? {
        let ImageWithCGSVGDocument = unsafeBitCast(UIImage.self.method(for: ImageWithCGSVGDocumentSEL), to: ImageWithCGSVGDocument.self)
        let image = ImageWithCGSVGDocument(UIImage.self, ImageWithCGSVGDocumentSEL, document)
        return image
    }
    
    public func draw(in context: CGContext) {
        draw(in: context, size: size)
    }
    
    public func draw(in context: CGContext, size target: CGSize) {

        var target = target
        
        let ratio = (
            x: target.width / size.width,
            y: target.height / size.height
        )
        
        let rect = (
            document: CGRect(origin: .zero, size: size), ()
        )

        let scale: (x: CGFloat, y: CGFloat)
        
        if target.width <= 0 {
            scale = (ratio.y, ratio.y)
            target.width = size.width * scale.x
        } else if target.height <= 0 {
            scale = (ratio.x, ratio.x)
            target.width = size.width * scale.y
        } else {
            let min = min(ratio.x, ratio.y)
            scale = (min, min)
            target.width = size.width * scale.x
            target.height = size.height * scale.y
        }

        let transform = (
            scale: CGAffineTransform(scaleX: scale.x, y: scale.y),
            aspect: CGAffineTransform(translationX: (target.width / scale.x - rect.document.width) / 2, y: (target.height / scale.y - rect.document.height) / 2)
        )
        
        context.translateBy(x: 0, y: target.height)
        context.scaleBy(x: 1, y: -1)
        context.concatenate(transform.scale)
        context.concatenate(transform.aspect)
        
        CGContextDrawSVGDocument(context, document)
    }
}

Can be used this class in UIKit? I'm trying to render a SVG downloaded from a remote server but I get this message:

Entity: line 1: parser error : Start tag expected, '<' not found
\377\330\377\340
^

This is my implementation:

let data = try Data(contentsOf: url)
if let svg = SVG(data) {
    let image = svg.image()
    let render = UIGraphicsImageRenderer(size: svg.size)
    let image2 = render.image { context in
        svg.draw(in: context.cgContext)
    }
    DispatchQueue.main.async {
        self.image = image2
    }
}

The app crashes inside of the draw() method, at this line:
CGContextDrawSVGDocument(context, document)

UPDATE: I found that the problem is with the image that I'm trying to download. Is there any problem with encoding types?
My original image is .utf8 (the one that cannot be assigned) and a one that worked for me (downloaded from internet) is isoLatin1.

Can be used this class in UIKit?

Yes.

This is my implementation:

I would recommend something like this:

final class SVGView: UIView {
  var svg: SVG
  init(_ svg: SVG) {
    self.svg = svg
    super.init(frame: .init(origin: .zero, size: svg.size))
    isOpaque = false
  }
  
  @available(*, unavailable) required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  override func draw(_ rect: CGRect) {
    guard let context = UIGraphicsGetCurrentContext() else { return }
    svg.draw(in: context, size: rect.size)
  }
}

UPDATE: I found that the problem is with the image that I'm trying to download. Is there any problem with encoding types?
My original image is .utf8 (the one that cannot be assigned) and a one that worked for me (downloaded from internet) is isoLatin1.

That is strange - are you able to share the SVG which fails to decode?

This is the image @ollieatkinson :