MediaApi.cs

private readonly IMediaService _mediaSvc = ApplicationContext.Current.Services.MediaService;

// Updating profile pic 
internal void UpdateProfilePic(int profileId, string picPath)
{
    if (profileId == 0) throw new ArgumentException("Error updating profile, no profile id in request");
    var contentItem = _contentSvc.GetById(profileId);

    // Set mediaitem
    var mediaFilename = contentItem.Name + Path.GetExtension(picPath);
    var mediaItem = GetMediaItem(contentItem.Name);
    using (var filestream = new FileStream(picPath, FileMode.Open))
    {
        mediaItem.SetValue("umbracoFile", mediaFilename, filestream);
        _mediaSvc.Save(mediaItem);
    }

    // Update profile item
    contentItem.SetValue("profilePic", mediaItem.Id);
    _contentSvc.PublishWithStatus(contentItem);
}

// Gets a media item by in a named folder, creates item if it's not there
private IMedia GetMediaItem(string profileName)
{
    var rootFolder = _umbHelper.TypedMediaAtRoot()
        .FirstOrDefault(m => m.Name == "Profilbilleder");
    if (rootFolder == null)
        throw new ArgumentOutOfRangeException("Could not find root folder for profile pics");
    // Find existing item
    var mediaContent = rootFolder.Children.FirstOrDefault(i => i.Name == profileName);
    if (mediaContent != null) return _mediaSvc.GetById(mediaContent.Id);
    // No mediaitem for this profile - create one
    return _mediaSvc.CreateMedia(profileName, rootFolder.Id, "Image");
}