Problem in accessing camera on Iphone

Hello All,

I have used below code to get image from either gallery or from camera. It works fine in both windows and Android platforms, but it's not working in Iphone. May I know what is the problem and how to resolve it.

public static class ImageUpload
{
public static IMediaPicker _mediaPicker;
public static MediaFile mediaFile;
public static IDevice _device;
public static readonly TaskScheduler _scheduler = TaskScheduler.FromCurrentSynchronizationContext();
public static string Status { get; set; }
public static string _path;

    ////////////////////////////////// Choose Image From Gallery //////////////////////////////////
    public static async Task<MediaFile> ChoosePicture(int maxPixel, string imageChosenType)
    {
        try
        {
            _mediaPicker = DependencyService.Get<IMediaPicker>() ?? Resolver.Resolve<IDevice>().MediaPicker;
            if (imageChosenType == Convert.ToString(ChooseImageFrom.Gallery))
            {

        // I am getting error in below line in Iphone       
                mediaFile = await _mediaPicker.SelectPhotoAsync(new CameraMediaStorageOptions
                {
                    DefaultCamera = CameraDevice.Front,
                    MaxPixelDimension = maxPixel
                });
            }
            else
            {  
        // I am getting error in below line in Iphone   
                mediaFile = await _mediaPicker.TakePhotoAsync(new CameraMediaStorageOptions
                {
                    DefaultCamera = CameraDevice.Front,
                    MaxPixelDimension = maxPixel
                });
            }
            return mediaFile;

            //uploadImg.Source = ImageSource.FromStream(() => mediaFile.Source);
            // _profilePicArray = DependencyService.Get<IimageToByteArray>().GetByteArrayFromImagePath(mediaFile.Path); 
        }
        catch (TaskCanceledException ex) 
        {
            throw ex;
        }
        catch (Exception ex)
        {
            /*
            if (ex.Message.ToLower().Contains("task") || ex.Message.Contains("Task"))
            {

            }
            else
            {
                throw ex;
            }
            */
            return null;
        }
    }


}

mediaFile has null, so that it occurs, how to resolve it?

Thanks,
Suneel Kumar Biyyapu.