Resize Image using vImage (Updated for Swift 5)

resize-vi.swift

extension UIImage {
    
    func resize(size: CGSize) -> UIImage? {
        
        guard let cgImage = self.cgImage else { return nil}
        
        var format = vImage_CGImageFormat(bitsPerComponent: 8, bitsPerPixel: 32, colorSpace: nil,
                                          bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
                                          version: 0, decode: nil, renderingIntent: CGColorRenderingIntent.defaultIntent)
        var sourceBuffer = vImage_Buffer()
        defer {
            if #available(iOS 13.0, *) {
                sourceBuffer.free()
            } else {
                sourceBuffer.data.deallocate()
            }
        }
        
        var error = vImageBuffer_InitWithCGImage(&sourceBuffer, &format, nil, cgImage, numericCast(kvImageNoFlags))
        guard error == kvImageNoError else { return nil }
        
        // create a destination buffer
        let scale = self.scale
        let destWidth = Int(size.width)
        let destHeight = Int(size.height)
        let bytesPerPixel = cgImage.bitsPerPixel / 8
        let destBytesPerRow = destWidth * bytesPerPixel
        let destData = UnsafeMutablePointer<UInt8>.allocate(capacity: destHeight * destBytesPerRow)
        defer {
            destData.deallocate()
        }
        var destBuffer = vImage_Buffer(data: destData, height: vImagePixelCount(destHeight), width: vImagePixelCount(destWidth), rowBytes: destBytesPerRow)
        
        // scale the image
        error = vImageScale_ARGB8888(&sourceBuffer, &destBuffer, nil, numericCast(kvImageHighQualityResampling))
        guard error == kvImageNoError else { return nil }
        
        // create a CGImage from vImage_Buffer
        guard let destCGImage = vImageCreateCGImageFromBuffer(&destBuffer, &format, nil, nil, numericCast(kvImageNoFlags), &error)?.takeRetainedValue() else { return nil}
        guard error == kvImageNoError else { return nil }
        
        // create a UIImage
        let resizedImage = UIImage(cgImage: destCGImage, scale: scale, orientation: self.imageOrientation)
        return resizedImage
    }
}

great job! cool, respect!