In iOS, a popup is shown from time to time that asks the user to join a Wi-Fi network.

![Select a Wi-Fi Network](https://i.stack.imgur.com/RgRc6.jpg)

I want to implement a similar popup with custom contents

* Title
* TableView with a varying amount of entries (if too many, with scrollbar)
* Cancel button
* Popup over an existing view (the popup is smaller than the view)
* How can such an effect be achieved? I guess that UIAlertView may be a good starting point. However, UIAlertView does not support subclassing

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> The UIAlertView class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified.
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