This line makes the is_iphone_request? method a helper method that is callable from any view.
这行代码将使 is_iphone_request? 方法成为助手方法，您可以从任何一个视图中调用它。
We use all these helper classes together with our data model to create our View class.
我们通过将所有这些helper类与数据模型一起使用，从而创建自己的view类。
When your action is called in the execute method, you must call a couple helper functions to update the specific view instance (if that is what your action is intended to do).
在execute方法中调用操作时，必须调用一对helper函数来更新特定的视图实例(如果这是操作的目的)。
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