Providing two functions, to let you store data to device, or fetch data from device, you can choose NSUserDefaults or Plist to handle the data. Plus, you can store and fetch custom class object.
提供两个函数，来方便开发者用一行代码存储、读取数据（本地存储），可选用 NSUserDefaults 或者 Plist，可以存储 Custom Class 实例。