PHImageManager maximum target size not working in Xamarin iOS

Question

I have the following code in my GMImagePickerController in FinishedPicking Event.

picker.FinishedPickingAssets += (s, args) =>
        {
            PHImageManager imageManager = new PHImageManager();
            PHImageRequestOptions imageOptions = new PHImageRequestOptions();
            imageOptions.DeliveryMode = PHImageRequestOptionsDeliveryMode.HighQualityFormat;
            imageOptions.ResizeMode = PHImageRequestOptionsResizeMode.Exact;
            foreach (var asset in args.Assets)
            {
                imageManager.RequestImageForAsset(asset,
                  new CGSize(asset.PixelWidth,asset.PixelHeight),
                  PHImageContentMode.Default,
                  imageOptions,
                  (image1, info) =>
                  {
                      if(count<1)
                      {
                          CommonFunction.AttachPhotoiOS(image1, eventRecordID, cp, "NormalImage");
                          count++;
                      }
                      //CallCommonFunctionAttachPhotoiOS(image1, eventRecordID);
                  });
                break;
            }
        };

As you can see I have already set the CGSize to the asset width and height, but still, when I debug and mouse over the image1 which is the retrieved image, the width and height is always 90 x 120 but not the original size of the asset. I have tried many ways and many images, the width and height seems like fixed forever. Which part has been done wrong? How can I get the original size of the image from it?