Swift Functional Programming - Second Edition

Error handling

Swift provides support to throw, catch, propagate, and manipulate recoverable errors at runtime.

Value types should conform to the Error protocol to be represented as errors. The following example presents some 4xx and 5xx HTTP errors as enum:

enum HttpError: Error {     case badRequest     case unauthorized     case forbidden     case requestTimeOut     case unsupportedMediaType     case internalServerError     case notImplemented     case badGateway     case serviceUnavailable } 

We will be able to throw errors using the throw keyword and mark functions that can throw errors with the throws keyword.

We can use a do-catch statement to handle errors by running a block of code. The following example presents JSON parsing error handling in a do-catch ...