How to perform affine transform on stream? - ios

Question

I want to rotate image, which I get from memoryStream.
I've tried to use UIView:
private Stream TransformImageFromStream(MemoryStream stream, CGAffineTransform transform)
{
var bytes = stream.ToBytes ();
var data = NSData.FromArray (bytes);
var image = UIImage.LoadFromData (data);
var uiImage = new UIImageView (image);
uiImage.Transform = transform;
var result = uiImage.Image.AsPNG ().AsStream ();
var testBytes = result.ToBytes ();
if (testBytes [0] == bytes [0])
{
// throw new Exception ("test failed");
}
return result;
}
But transform never applies as it always do with UIView within graphic canvas.
I've found somewhere that it will work with using ApplyTransform directly to CIImage
private Stream TransformImageFromStream(MemoryStream stream, CGAffineTransform transform)
{
var bytes = stream.ToBytes ();
using (var data = NSData.FromArray (bytes))
using (var ciImage = CIImage.FromData (data))
using (var transformedImage = ciImage.ImageByApplyingTransform (transform))
using (var uiImage = UIImage.FromImage(ciImage))
using (var uiImageView = new UIImageView(uiImage))
{
var result = uiImage.AsPNG ();
return null;
}
}
But UIImage doesnt want to convert it AsPng() in order to convert it to stream. In this case I've noticed that CGImage is empty, most of properties set to 0. Perhaps, there is some way to convert the CIImage itself, without any wrapping?
I have no more clues to what to do.