Subclassing UIView in Swift

Provide the functionality that a standard UIView just can’t

Here are Apple’s Subclassing notes from their documentation:

The UIView class is a key subclassing point for visual content that also requires user interactions. Although there are many good reasons to subclass UIView, it is recommended that you do so only when the basic UIView class or the standard system views do not provide the capabilities that you need. Subclassing requires more work on your part to implement the view and to tune its performance.