programmatic-uikit-layout

Programmatic UIKit Layout with Auto Layout

Overview

Programmatic UIKit layout with anchors provides type-safe, maintainable UI code used by production apps at scale. Stack views solve 50%+ of layout problems, anchors provide compile-time safety, design systems ensure consistency.

Core principle: Anchors-only (no Visual Format Language), stack-first composition, reusable components with centralized spacing/colors.

Foundation Setup

Step 1: Disable Storyboards

Remove Main.storyboard:

1. Delete Main.storyboard file
2. In Info.plist, delete "Main storyboard file base name" entry
3. Delete "Storyboard Name" in Target → Info → Custom iOS Target Properties

Configure SceneDelegate:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    var window: UIWindow?

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let windowScene = (scene as? UIWindowScene) else { return }

        window = UIWindow(windowScene: windowScene)
        window?.rootViewController = MainViewController()
        window?.makeKeyAndVisible()
    }
}

Step 2: Essential UIView Setup

CRITICAL: Every view needs translatesAutoresizingMaskIntoConstraints = false

// ❌ WRONG: Constraints conflict with autoresizing mask
let label = UILabel()
view.addSubview(label)
label.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
// Runtime error: conflicting constraints

// ✅ CORRECT: Disable autoresizing mask
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(label)
label.topAnchor.constraint(equalTo: view.topAnchor).isActive = true

Rule: Set translatesAutoresizingMaskIntoConstraints = false BEFORE adding constraints.

Layout Anchors (Preferred Method)

Why Anchors Over NSLayoutConstraint

Feature	Layout Anchors	NSLayoutConstraint
Type safety	✅ Compile-time checks	❌ Runtime errors
Readability	✅ Fluent API	❌ Verbose initializer
Error prevention	✅ Can't mix X/Y axes	❌ Easy to make mistakes