Question

difference between subclassinf pageviewcontroller and creting a object of pageviewcontroller

Answer 1

Viewcontroller is plain controller object managing its views, PageViewController in turn it container view controller which can hold/show multiple viewcontroller for page based navigation. You will observe that PageViewController is also subclass of viewcontroller itself. refer for creating custom/container viewcontroller. PageViewController is nothing but such container viewcontroller nothing more. If you put some efforts you can build your own too.