@EnvironmentObject for shared state in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a shared data model using @EnvironmentObject in SwiftUI.

iOS Swift

struct ContentView: View {
  @EnvironmentObject var model: [1]

  var body: some View {
    Text(model.title)
  }
}

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AStateObject

BSharedDataModel

CObservedObject

DEnvironment

Attempts:

3 left

💡 Hint

Common Mistakes

Using @StateObject or @ObservedObject instead of @EnvironmentObject

Using a wrong type name that does not match the shared model

Use the exact class name of the shared data model with @EnvironmentObject to access shared state.

2fill in blank

medium

Complete the code to inject the shared model into the environment in the app's root view.

iOS Swift

MyApp()
  .environmentObject([1]())

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ASharedDataModel

BContentView

CStateObject

DEnvironmentObject

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a view type instead of the model

Using property wrapper names instead of the model class

You create an instance of the shared data model class and inject it with .environmentObject().

3fill in blank

hard

Fix the error in accessing the shared model property in a child view.

iOS Swift

struct DetailView: View {
  var model: [1]

  var body: some View {
    Text(model.title)
  }
}

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A@EnvironmentObject SharedDataModel

B@ObservedObject SharedDataModel

C@StateObject SharedDataModel

DSharedDataModel

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the @EnvironmentObject wrapper

Using @StateObject or @ObservedObject in child views

Child views must declare the shared model with @EnvironmentObject to access the injected shared state.

4fill in blank

hard

Fill both blanks to update the shared model's property and notify views.

iOS Swift

class SharedDataModel: ObservableObject {
  @Published var title = "Hello"

  func updateTitle(to newTitle: String) {
    self.title [1] newTitle
  }
}

struct ContentView: View {
  @EnvironmentObject var model: SharedDataModel

  var body: some View {
    Button(action: {
      model.title [2] "Welcome"
    }) {
      Text("Change Title")
    }
  }
}

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A=

B+=

C-=

D*=

Attempts:

3 left

💡 Hint

Common Mistakes

Using += or other operators that do not replace the value

Forgetting to assign the new value

Use = to assign a new value to the published property so views update.

5fill in blank

hard

Fill all three blanks to create a SwiftUI view that reads and updates shared state correctly.

iOS Swift

struct ProfileView: View {
  @EnvironmentObject var model: [1]

  var body: some View {
    VStack {
      Text(model.[2])
      Button("Update") {
        model.[3] = "Updated"
      }
    }
  }
}

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ASharedDataModel

Btitle

DupdateTitle

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names instead of property names

Using wrong property names that do not exist

Use the shared model class name, access the published property 'title', and assign a new value to it.