lolgear / WizardRegistrationSwiftUI

This repository is inspired by Apple WWDC "Combine in Practice" app.

WizardRegistrationSwiftUI

This repository is inspired by Apple WWDC "Combine in Practice" app.

Purpose

This project demonstrates different approaches of using SwiftUI and Combine frameworks. We can divide approaches into several groups.

1. Pure SwiftUI.
2. SwiftUI with Publishers.

Pure SwiftUI.

In this approach we only use didSet hooks on our data to react on UI updates. It is fairly limited, but can provide basic building blocks to achieve simple apps with single source of truth.

Details

//MARK: Model
class Model : BindableObject {
  var name: String {didSet {didChange.send()}}
  var password: String {didSet {didChange.send()}}
  var passwordAgain: String {didSet {didChange.send()}}
}

//MARK: View
struct SomeView : View {
  @Binding var model: Model.PureSwiftUI
  var body : some View {
    SomeView.Child(model: $model.childValue)
  }
}

SwiftUI with Publishers.

On the other hand, we can combine @State property wrapper on view with @Published property wrapper on model. It is required to provide achieve exclusive access on propetries that view utilize.

Details

//MARK: Model
class Model : BindableObject {
  @Published var name: String = ""
  @Published var password: String = ""
  @Published var passwordAgain: String = ""
  
  // We must set publisher to any value, because we need to combine publishers in `init` 
  var didChange: AnyPublisher<Result<(String, String), Error>, Never> = Publishers.Empty().eraseToAnyPublisher()
  
  init() {
    self.name = ""
    self.password = ""
    self.passwordAgain = ""
    
    self.didChange = `...`
  }
}

//MARK: View
struct SomeView : View {
  @Binding var model: Model
  @State var name: String = ""
  @State var password: String = ""
  @State var passwordAgain: String = ""
  @State var error: Error?
  
  var body : some View {
    Form {
      SomeView.Child(model: Binding(
        getValue: { return self.name }
        setValue: { value in 
          self.name = value
          self.model.name = value
        }
      ))
    }.onReceive(self.model.didChange) { value in
      // process value
  }
}