/// 缓存图片
 
  private func cacheImages(viewmodels : [Statusviewmodel]) {
 
    // 0.创建group
 
    let group = dispatch_group_create()
 
   
 
    // 1.缓存图片
 
    for viewmodel in viewmodels {
 
      for picURL in viewmodel.picURLs {
 
        dispatch_group_enter(group)
 
        SDWebImageManager.sharedManager().downloadImageWithURL(picURL,options: [],progress: nil,completed: { (_,_,_) -> Void in
 
          dispatch_group_leave(group)
 
        })
 
      }
 
    }
 
   
 
    // 2.刷新表格
 
    dispatch_group_notify(group,dispatch_get_main_queue()) { () -> Void in
 
      self.tableView.reloadData()
 
    }
 
  }