Transparency of UIImage is Missed when Converting to Texture - ios

Question

I am converting a UIImage to texture, then I am converting that texture to UIImage. The transparent areas are replaced with black color.
The function I am using to convert a UIImage to texture.
func imageToTexture(imageNamed: String, device: MTLDevice) -> MTLTexture {
let bytesPerPixel = 4
let bitsPerComponent = 8
var image = UIImage(named: imageNamed)!
let width = Int(image.size.width)
let height = Int(image.size.height)
let bounds = CGRect(x: 0, y: 0, width: CGFloat(width), height: CGFloat(height))
var rowBytes = width * bytesPerPixel
var colorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(data: nil, width: width, height: height, bitsPerComponent: bitsPerComponent, bytesPerRow: rowBytes, space: colorSpace, bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue).rawValue)
context!.clear(bounds)
context?.translateBy(x: CGFloat(width), y: CGFloat(height))
// CGContextTranslateCTM(context!, CGFloat(width), CGFloat(height))
context?.scaleBy(x: -1.0, y: -1.0)
// CGContextScaleCTM(context!, -1.0, -1.0)
context?.draw(image.cgImage!, in: bounds)
// CGContextDrawImage(context, bounds, image.CGImage)
var texDescriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: .bgra8Unorm , width: width, height: height, mipmapped: true)
var texture = device.makeTexture(descriptor: texDescriptor)
texture?.label = imageNamed
// var pixelsData = CGBitmapContextGetData(context!)
var pixelsData = context?.data
var region = MTLRegionMake2D(0, 0, width, height)
texture?.replace(region: region, mipmapLevel: 0, withBytes: pixelsData!, bytesPerRow: rowBytes)
makeImage(from: texture!)
return texture!
}
The function converting texture to UIImage. After changing UIImage to texture, I am calling to convert it back to UIImage. It is not.
func makeImage(from texture: MTLTexture) -> UIImage? {
let width = texture.width
let height = texture.height
let bytesPerRow = width * 4
let data = UnsafeMutableRawPointer.allocate(bytes: bytesPerRow * height, alignedTo: 4)
defer {
data.deallocate(bytes: bytesPerRow * height, alignedTo: 4)
}
let region = MTLRegionMake2D(0, 0, width, height)
texture.getBytes(data, bytesPerRow: bytesPerRow, from: region, mipmapLevel: 0)
var buffer = vImage_Buffer(data: data, height: UInt(height), width: UInt(width), rowBytes: bytesPerRow)
let map: [UInt8] = [2, 1, 0, 3]
vImagePermuteChannels_ARGB8888(&buffer, &buffer, map, 0)
guard let colorSpace = CGColorSpace(name: CGColorSpace.genericRGBLinear) else { return nil }
guard let context = CGContext(data: data, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow,
space: colorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue) else { return nil }
guard let cgImage = context.makeImage() else { return nil }
let x = UIImage(cgImage: cgImage)
return x;
}
Here the output image is black in the transparent areas. I don't know where I messed up.