Articles, podcasts and news about Swift development, by John Sundell.

Grouping throwing expressions using tuples

Published on 15 Feb 2019
Basics article available: Error Handling

Tuples can not only be super useful in order to group multiple related local variables into one, but can also be a great way to combine several throwing expressions.

// Here we have three highly related expressions that are
// all throwing, requiring separate assignments and separate
// 'try' keywords:
let contentFolder = try Folder.current.subfolder(named: "content")
let templatesFolder = try Folder.current.subfolder(named: "templates")
let output = try Folder.current.createSubfolderIfNeeded(withName: "output")

// By combining them all into a tuple, we only need one
// 'try', and can easily group our data into a single,
// lightweight container:
let folders = try (
    content: Folder.current.subfolder(named: "content"),
    templates: Folder.current.subfolder(named: "templates"),
    output: Folder.current.createSubfolderIfNeeded(withName: "output")

// The call sites also become really nice and clean, with
// increased "namespacing" for our local variables:
readFiles(in: folders.content)
loadTemplates(from: folders.templates)

Support Swift by Sundell by checking out this sponsor:

Genius Scan SDK

Genius Scan SDK: Add a powerful document scanner to any iOS app. Genius Scan’s SDK features advanced image processing that’s the result of over 10 years of research and development and can be fully customized and integrated into your app with just one line of code. Mention Swift by Sundell when requesting a free demo to get a 20% discount on your license for a whole year.