URLComponents breaks URLs with path parameters.
Any variable can have a getter/setter or observers, not only properties.
Data unbinding cannot be safely done for UITableViewCell or UICollectionViewCell.
When override gets involved, overload resolution becomes quite a puzzle.
Recursive functions are elegant but dangerous to use in Swift.
The big picture of Objective-C invocation forwarding.
Any LiteralConvertible can be enumeration raw values.
Defaulted arguments are allowed to be reordered.
Apple's documentation of CABasicAnimation value interpolation is wrong.
The experience of switching keyboards is bad for multilingual users. I propose an enhanced design.