/views

SwiftUI Views

• Strongly prefer to avoid breaking up view bodies using computed properties or methods that return some View, even if @ViewBuilder is used. Extract them into separate View structs instead, placing each into its own file.
• Flag body properties that are excessively long; they should be broken into extracted subviews.
• Button actions should be extracted from view bodies into separate methods, to avoid mixing layout and logic.
• Similarly, general business logic should not live inline in task(), onAppear() or elsewhere in body.
• Prefer to place view logic into view models or similar, so it can be tested.
• Each type (struct, class, enum) should be in its own Swift file. Flag files containing multiple type definitions.
• Unless a full-screen editing experience is required, prefer using TextField with axis: .vertical to using TextEditor, because it allows placeholder text. If a specific minimum height is required for TextField, use something like lineLimit(5...).
• If a button action can be provided directly as an action parameter, do so. For example: Button("Label", systemImage: "plus", action: myAction) is preferred over Button("Label", systemImage: "plus") { action() }.
• When rendering SwiftUI views to images, strongly prefer ImageRenderer over UIGraphicsImageRenderer.
• #Preview should be used for previews, not the legacy PreviewProvider protocol.
• When using TabView(selection:), use a binding to a property that stores an enum rather than an integer or string. For example, Tab("Home", systemImage: "house", value: .home) is better than Tab("Home", systemImage: "house", value: 0).
• Strongly prefer to avoid breaking up view bodies using computed properties or methods that return some View, even if @ViewBuilder is used. Extract them into separate View structs instead, placing each into its own file. (Yes, this is repeated, but it’s so important it needs to be mentioned twice.)

Animating views

• Strongly prefer to use the @Animatable macro over creating animatableData manually – the macro automatically adds conformance to the Animatable protocol and creates the correct animatableData property. If some properties should not or cannot be animated (e.g. Booleans, integers, etc), mark them @AnimatableIgnored.
• Never use animation(_ animation: Animation?); always provide a value to watch, such as .animation(.bouncy, value: score).
• Chaining animations must be done using a completion closure passed to withAnimation(), rather than trying to execute multiple withAnimation() calls using delays.

For example:

Button("Animate Me") {
    withAnimation {
        scale = 2
    } completion: {
        withAnimation {
            scale = 1
        }
    }
}