Getting ready

Before starting to learn how to handle errors in Swift, you first have to be familiar with how to represent in errors that are going to happen in your program. Swift provides you with a protocol called ErrorType that your errors types should adopt. Then, to represent errors, here comes the role of enumerations to help you. You create a new enum, which lists all error cases, and this enum should conform to the ErrorType protocol. The syntax of using enum with ErrorType will be something like this:

enum DBConnectionError: ErrorType{ 
  case ConnectionClosed 
  case DBNotExist 
  case DBNotWritable 
} 

As we see it's pretty straightforward. You create enum representing the error that conforms to ErrorType protocol, and then list all errors as cases in the enum.