Swift by Sundell, created and run by John Sundell since 2017, shares free articles, tips, podcasts, and videos on Swift, iOS, and Mac development for all skill levels. John is a passionate developer and designer, freelances in iOS/Mac development, and co-hosts the Stacktrace podcast.
An incremental SwiftUI design system via composition: start with a generic Row, compose TextFieldRow and a reusable TextInputView that selects TextField/SecureField using UITextContentType and @FocusState. Evaluate ViewBuilder closures in init. Use environment-driven config (RowStyle, colors) via View modifiers.
How let vs var on structs impact memberwise init, default values, and Codable: let optionals need explicit args; let with defaults can’t be overridden/decoded. Use a custom init or a Readonly property wrapper (Codable). inout shows mutability. Prefer vars; keep stable IDs let.
Shows how to decode Swift models that need data not present in the payload. Instead of optional fields or a Partial type, use DecodableWithConfiguration to inject required values. Adds a JSONDecoder shim using userInfo for iOS 15–16. Example uses URLSession, async/await.
Explores SwiftUI’s @ViewBuilder: implicit use in View.body, applying it to custom containers, making sections optional with EmptyView or default args, caveats (closure-to-view only for stored props, multiple roots behave like Group), and a perf tip to resolve closures in init.
Shows how defer guarantees cleanup across throws and async/await. Examples: close a Database connection, reset isLoading in an actor, and coalesce duplicate loads using a Task dictionary keyed by ID. For throws-only, Result can flatten flow. Note: defer runs at scope exit.
Swift by Sundell is returning. To address outdated/overlapping coverage, all previous posts were moved into a preserved Archive to reset topics. With six months of writing time funded by Genius Scan, new Swift articles are rolling out, starting with Modern URL construction in Swift.
Safer URL construction in Swift: replace fragile URL(string:) with URL(init: StaticString) that fatalErrors with context, then a #staticURL macro to compile‑time validate literals. For dynamic URLs, use URL.appending(components:, queryItems:) and new directory constants (iOS 16+). Trade off macro complexity vs safety.