upscale an image using scale2x in swift

main.swift
func scale2x(image: UIImage) -> UIImage? {
    guard let cgImage = image.cgImage else { return nil }
    
    let width = cgImage.width * 2
    let height = cgImage.height * 2
    let bytesPerPixel = 4
    let bytesPerRow = bytesPerPixel * width
    let bitmapInfo = cgImage.bitmapInfo.rawValue
    
    let context = CGContext(data: nil, width: width, height: height, bitsPerComponent: cgImage.bitsPerComponent, bytesPerRow: bytesPerRow, space: cgImage.colorSpace!, bitmapInfo: bitmapInfo)!
    
    context.interpolationQuality = .none
    context.draw(cgImage, in: CGRect(x: 0, y: 0, width: width/2, height: height/2))
    
    var scaledImage = context.makeImage().flatMap { UIImage(cgImage: $0) }
    
    // Repeat the scaling process to get a better scale
    for _ in 0..<1 {
        guard let cgImage = scaledImage?.cgImage else { return nil }
        
        let width = cgImage.width * 2
        let height = cgImage.height * 2
        let bytesPerPixel = 4
        let bytesPerRow = bytesPerPixel * width
        let bitmapInfo = cgImage.bitmapInfo.rawValue
        
        let context = CGContext(data: nil, width: width, height: height, bitsPerComponent: cgImage.bitsPerComponent, bytesPerRow: bytesPerRow, space: cgImage.colorSpace!, bitmapInfo: bitmapInfo)!
        
        context.interpolationQuality = .none
        context.draw(cgImage, in: CGRect(x: 0, y: 0, width: width/2, height: height/2))
        
        scaledImage = context.makeImage().flatMap { UIImage(cgImage: $0) }
    }
    
    return scaledImage
}
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