swiftui - evanmoran/quick GitHub Wiki

@State              The view owns the data (usually a simple value type like string or double)

@Binding            The simple value data (string, float) is passed to the view on construction and creates a two way binding to it

@Published          Model classes define these to publish changes to value types

@StateObject        The view owns the model data but this is a full class that implements `ObservableObject`  

@ObservedObject     The model data is passed to the view on construction. Must implement `ObservableObject` 
                    (our normal case! The same as @Binding with class types) 

@EnvironmentObject  Same as @Binding (passed in model data implementing ObservableObject), 
                     but comes from a global environment system instead 

class MyView: View {
   @State var state: String        
   @Binding var binded: String 
   @StateObject var model: Model = Model()


   init() {
       // State
       let getState = state                              // String (same as $state.wrappedValue)
       let dollarState = $state                          // Binding<String>
       let underscoreState = _state                      // State<String>
       let dollarStateWrapped = $state.wrappedValue      // String
       let dollarStateProjected = $state.projectedValue  // Binding<String>

       // Binded
       let dollarBinded = $binded                        // Binding<String>
       let underscoreBinded = _binded                    // Binding<String>
       let getBinded = binded                            // String (same as $binded.wrappedValue)
       let dollarBindedWrapped = $binded.wrappedValue    // String
       
       // Model
       let getModel = model                                        // Model
       let dollarModel = $model                                    // ObservedObject<Model>.Wrapper
       let underscoreModel = _model                                // StateObject<Model>
       let getModelPublished = model.published                     // String
       let getModelDollarPublished = model.$published              // Published<String>.Publisher
       let dollarModelPublished = $model.published                 // Binding<String>
       // let dollarModelUnderscorePublished = $model._published   // private / inaccessible 
       // let dollarModelDollarPublished = $model.$published       // Binding<Published<String>.Publisher> (do not use?)
   }
}
class Model: ObservableObject {
   
   @Published var published: String
   private var cancelSet = Set<AnyCancellable>()

   init() {
       // Published
       let dollarPublished = $published                  // Published<String>.Publisher
       let underscorePublished = _published              // Published<String>
       let getPublished = published                      // String

       // Debounce model
       self.$published
            .debounce(for: .seconds(2), scheduler: RunLoop.main)
            .sink { [weak self] (newValue) in
                print("Debounce published value to newValue: \(newValue)")
            }
            .store(in: &cancelSet)
   }
}