Swift on Robert Harrison

Swift tip: Properly deprecating code

Fri, 18 Jul 2025 18:00:00 -0700

As codebases evolve, we inevitably accumulate functions, classes, and APIs that need to be removed or replaced. Use @available(*, deprecated, message: "...") to mark functions as deprecated in your Swift projects:

@available(*, deprecated, message: "This function will be removed in a future release.")
func oldFunction() {
    // legacy code
}

This gives developers, including your future self, a clear heads-up about upcoming changes while keeping code functional during the transition period. The compiler will show warnings but won’t break existing builds.

Swift Singleton with @unchecked Sendable

Sat, 01 Mar 2025 14:35:00 -0700

A singleton 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.

Pre-Swift 6, a singleton could be written like so:

Organize Code with Local Swift Packages

Wed, 25 Sep 2024 09:17:00 -0700

There are several benefits to organizing your code into modules:

Readability
Testability
Reusability
Maintainability
And more …

By using an Xcode Workspace and Swift Packages, a monolithic project can be split up and organized, into smaller modules or packages. Utilities, for example, can go in one package, and the Data Layer can go in another package.

Swift Packages can be local or remote. If the module can be used by other projects or teams, then consider using a remote package. In which case, the remote package will require its own git repository. If the module is only usable by the main application, then use a local package. The local package will live within the git repository of the main application. In this article, we’re going to use a local package.

Manage Multiple Projects with an Xcode Workspace

Mon, 23 Sep 2024 15:38:00 -0700

By default, Xcode projects use an .xcodeproj file to organize and structure the project. The project file contains code, resources, settings and targets for building a product.

What if your project needs to reference another project? For example, prior to building your main app, you must first compile and link a library. Use an Xcode Workspace (.xcworkspace) to manage the dependencies between multiple projects. Xcode can use the workspace to compile the library first, then link it to your app. If your project uses Cocoapods, then it’s using a Workspace.

SwiftUI Toggle

Tue, 22 Feb 2022 11:53:00 -0800

This article describes how to use the SwiftUI Toggle. By the end of the article you will have learned how to embed Toggle in a child View and perform the Toggle’s action in a parent View.

Let’s start with the basics. Here is a variation of the example in the official documentation:

@State private var faceIdEnabled = false
var body: some View {
    Toggle(isOn: $faceIdEnabled) {
        Text("Face ID")
    }
}

The above code will show a toggle control with “Face ID” for the title. By using a two-way binding on faceIdEnabled, we control if the toggle is on or off.