https://robertharrison.ca/tags/concurrency/ Recent content in Concurrency on Robert Harrison Hugo en-us Sat, 01 Mar 2025 14:35:00 -0700 https://robertharrison.ca/blog/swift-singleton-with-unchecked-sendable/ Sat, 01 Mar 2025 14:35:00 -0700 https://robertharrison.ca/blog/swift-singleton-with-unchecked-sendable/ <p>A <strong>singleton</strong> is a design pattern that ensures there is only one instance of a class. While convenient, there are drawbacks to using singletons, which are well documented elsewhere. Swift 6 provides some approaches to replacing Singletons, such as Actor. Sometimes, you run into a situation, such as re-using legacy code, where using a Singleton is preferable over refactoring to modern Swift techniques.</p> <p>Pre-Swift 6, a singleton could be written like so:</p>