CIImage+Blur.swift

private func cameraPreviewObfuscationImage(from image: CIImage, with blurRadius: CGFloat, at targetSize: CGSize) -> UIImage? {
    var blurAdjustedTargetSize = targetSize

    if targetSize.width > targetSize.height {
        blurAdjustedTargetSize.height += blurRadius * 2
    } else {
        blurAdjustedTargetSize.width += blurRadius * 2
    }

    let croppedImage = image.cropped(to: AVMakeRect(aspectRatio: blurAdjustedTargetSize, insideRect: image.extent))

    let targetScaledSize = targetSize.aspectFill(within: blurAdjustedTargetSize)
    let resizedImage = croppedImage.applyingFilter(
        "CILanczosScaleTransform",
        parameters: [
            kCIInputScaleKey: max(
                targetScaledSize.width / croppedImage.extent.width,
                targetScaledSize.height / croppedImage.extent.height
            ),
            kCIInputAspectRatioKey: 1
        ]
    )

    let blurredImage = resizedImage
        .clampedToExtent()
        .applyingFilter(
            "CIGaussianBlur",
            parameters: [
                kCIInputRadiusKey: blurRadius
            ]
        )
        .cropped(to: resizedImage.extent)

    guard let outputImage = coreImageContext.createCGImage(blurredImage, from: blurredImage.extent) else { return nil }
    return UIImage(cgImage: outputImage)
}