SweetUI 🍬

SweetUI adds a little sugar to UIKit. Goals:

🍬 Thin abstraction on top of UIKit (i.e. syntactic sugar) SweetUI only depends on Foundation, UIKit and Combine. The expected behaviour of UIKit classes remains unchanged. This means that SweetUI features can be adopted incrementally.
🚫 Banish storyboards and nibs SweetUI view and view controller subclasses must be defined entirely in code. By subclassing from SweetUI's View and ViewController classes you'll be saved from dealing with init(coder:) and init(nibName:bundle:).
📐 Declarative style for view layout Declarative style for view layout is easier to more concise than imperative style. A layout created using SweetUI is a standard UIKit layout so it can be changed and updated using standard UIKit methods. SweetUI provides views layout views (e.g. HStack) and modifiers that allow standard UIKit view layouts to be expressed declaratively. In most cases you'll never need to directly deal with NSLayoutConstraints.
🇺🇳 Integrates with Combine for state management Combine enables SweetUI to reduce the amount boilerplate code need to keep views up to date. SweetUI also aims to handle storing Cancellables reducing boiler plate code even further.
🎁 And more! Other features include:
- Modal, sheet and popover presentation with async/await
- Management of UIViewController properties (e.g. title, toolbar, navigationItem, tabBarItem) with Combine
- FlowController for managing a sequence of view controllers
- Keyboard avoidance
- Declarative interfaces for UICollectionViewCompositionalLayout and UICollectionViewCompositionalLayout.list
- LayoutView for creating reusable layout templates
- Retain cycle detection for easier debugging

Example

The follow code shows a simple ViewController subclass. Note:

The single init (neither init(nibName:bundle:) or init(coder:) are required)
The view is declared inline and in a declarative style.

import UIKit
import SweetUI


final class SimpleExampleViewController: ViewController {

    @Published var name: String

    lazy var rootView = ZStack(alignment: .center) {
        VStack(alignment: .center) {
            UILabel()
                .font(.largeTitle)
                .text("Hello \(name)!")
            UILabel()
                .font(.subheadline)
                .text("Welcome to SweetUI")
        }
    }
    
    init(name: String) {
        self.name = name
        super.init()
    }
}

The Demo app contains more examples of what's possible with SweetUI.

Miscellaneous Notes

How to replace main.storyboard with code

Delete Main.Storyboard from the project
Navigate to Project settings -> The target for the app -> Build Settings
- Remove the row 'UIKit Main Storyboard File Base Name'
In Info.plist navigate to 'Application Scene Manifest -> Scene Configuration -> Application Session Role -> Item 0' and delete the row 'Storyboard Name'
In SceneDelegate.swift, replace the implementation of scene(_ scene:willConnectTo:options:) with:

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let scene = scene as? UIWindowScene else {
            preconditionFailure("Unexpected scene type \(Self.self) can only connect to a UIWindowScene.")
        }
        let window = UIWindow(windowScene: scene)
        self.window = window
        window.windowScene = scene
        window.rootViewController = RootViewController() // where RootViewController is the app's initial viewController.
        window.makeKeyAndVisible()
    }

Adding `ViewBodyProvider` to an existing view

The reccommend way to use declarative view layout is to subclass one of the provided abstract classes: View, Control, CollectionViewCell and CollectionReusableView. If it is not possible to subclass from one of these classes then there are two alternatives approaches:

Use composition. E.G. create a new view subclass and add an instance as a subview to the existing view.
Make the view conform to ViewBodyProvider. ViewBodyProvider requires the conforming class to be final and initializeBody() to be called at the end of the designated init, E.G.:

final class CustomControl: UIControl, ViewBodyProvider {

    let body = UILabel()
        .text("Hiya!")

    init() {
        super.init(frame: .zero)
        initializeBodyHosting()
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

Fixes for `Circular reference` error

Create a method on the root object
Communicate the data via a Combine Publisher

BenedictC/SweetUI