iPhone网络应用程序的最佳客户端数据存储？

I am building a web app targeting the iPhone. It is similar to a To Do list. I need the application to be able to work offline, i.e., it should allow the user to add/edit/delete entries when there is no connection to the server, which will later get synced when the server is online again.I am building a web app targeting the iPhone. I