UIAlertView in Swift closures

UIAlertView has been deprecated in iOS 8.0 in favour of UIAlertController — but one still needs UIAlertView if iOS 7 support is required.

Using UIAlertViewDelegate is a bit cumbersome and whilst lots of Objective-C implementation with blocks are available, I needed one for Swift.

So here is my solution — a simple implementation of UIAlerView with Swift closures.