Defining Custom Errors With Advanced Descriptions In Swift

It’s a lot more that we can do with errors than just printing them in the console

Gabriel Theodoropoulos
6 min readAug 20, 2024
Photo by Miguel Á. Padriñán from Pexels: https://www.pexels.com/photo/close-up-shot-of-keyboard-buttons-2882552/

Swift provides a powerful mechanism for defining our own custom errors, allowing for better error handling and creating more informative and user-friendly errors in our applications. This capability is crucial when we aim to enhance the robustness and usability of Swift-based projects. By crafting proper custom errors, we can guide users with clarity and precision, significantly improving the overall user experience.

In this post, we’ll dive into the essentials of defining custom errors in Swift, exploring particular aspects and meeting some not so well-known, yet quite valuable APIs. Through practical examples and detailed explanations, you’ll get the knowledge that will let you write more reliable, as well as more intuitive for your users software.

Creating a custom error type

Defining custom errors requires the implementation of a custom type, and more particularly of an enumeration. This must mandatorily conform to the Error protocol for an important reason; without that conformance the cases defined in the enum won’t be catchable in a do-catch statement, which is the ultimate goal when specifying custom errors.

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Gabriel Theodoropoulos

An iOS & macOS app maker writing code in Swift. Author of countless programming tutorials. Content creator. https://serialcoder.dev