laevandus

extension Publisher where Self.Failure == Never {
    public func notifyObjectWillChange(_ objectWillChange: ObservableObjectPublisher) -> AnyCancellable {
        return self.sink { _ in
            objectWillChange.send()
        }
    }
}

laevandus

extension ContentView {
    final class ViewModel: ObservableObject {
        private let package: Package
        private var cancellables = [AnyCancellable]()
        
        init(package: Package) {
            self.package = package
            
            // Model -> View Model
            package.recipient.publisher(for: \.firstName)

laevandus

struct InputView: View {
    let title: String
    var placeholder: String = ""
    let value: Binding<String>
    
    var body: some View {
        VStack {
            HStack {
                Text(title)
                    .font(.subheadline)

laevandus

struct ContentView: View {
    @StateObject var viewModel = ViewModel(package: .makeExample())
    
    var body: some View {
        ScrollView {
            VStack(spacing: 16) {
                Text("Recipient")
                    .font(.headline)
                InputView(title: "First name",
                          value: $viewModel.recipientFirstName)

laevandus

final class Package: NSObject {
  @objc dynamic var recipient = Person()
  @objc dynamic var sender = Person()
  @objc dynamic var contents = [PackageContent]()
}

final class Person: NSObject {
  @objc dynamic var firstName: String = ""
  @objc dynamic var lastName: String = ""
  @objc dynamic var postalAddress = CNPostalAddress()

laevandus

// MARK: View

struct PackageCombineModelView: View {
    @StateObject var viewModel: ViewModel
    
    var body: some View {
        Form {
            TextField("First name", text: $viewModel.firstName)
            Text(viewModel.modelDescription)
        }

laevandus

// MARK: View

struct PackageKVOModelView: View {
    @StateObject var viewModel: ViewModel
    
    var body: some View {
        Form {
            TextField("First name", text: $viewModel.firstName)
            Text(viewModel.modelDescription)
        }

laevandus

struct ImageScaler {
  static func scaleToFill(_ image: UIImage, in targetSize: CGSize, from fromRect: CGRect = .zero) -> UIImage {
    let rect = fromRect.isEmpty ? CGRect(origin: .zero, size: image.size) : fromRect
    let scaledRect = rect.scaled(toFillSize: targetSize)
    return scale(image, fromRect: scaledRect, targetSize: targetSize)
  }
    
  private static func scale(_ image: UIImage, fromRect: CGRect = .zero, targetSize: CGSize) -> UIImage {
    let renderer = UIGraphicsImageRenderer(size: targetSize)
    return renderer.image { context in

laevandus

extension CGRect {
  func scaled(toFillSize targetSize: CGSize) -> CGRect {
    var scaledRect = self
    switch (size.aspect, targetSize.aspect) {
    case (.portrait, .portrait), (.portrait, .square):
      scaledRect.size.height = width / targetSize.aspectRatio
      scaledRect.size.width = width
      if scaledRect.height > height {
        scaledRect.size = size
      }

laevandus

extension CGSize {
  enum Aspect {
    case portrait, landscape, square
  }  
  var aspect: Aspect {
    switch width / height {
    case 1.0:
      return .square
    case 1.0...:
      return .landscape