Built-in property wrappers (@State, @Published) in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a state variable in a SwiftUI view.

Swift

struct ContentView: View {
    [1] var count = 0

    var body: some View {
        Text("Count: \(count)")
    }
}

Drag options to blanks, or click blank then click option'

A@State

B@Published

C@Binding

D@ObservedObject

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Published inside a View struct instead of @State.

Forgetting the @ symbol before the property wrapper.

Use @State to declare a local state variable inside a SwiftUI view.

2fill in blank

medium

Complete the code to declare a published property in an ObservableObject class.

Swift

class Counter: ObservableObject {
    [1] var value = 0
}

Drag options to blanks, or click blank then click option'

A@Published

B@EnvironmentObject

C@Binding

D@State

Attempts:

3 left

💡 Hint

Common Mistakes

Using @State inside a class instead of @Published.

Not conforming the class to ObservableObject.

Use @Published to mark properties that notify views when they change in ObservableObject classes.

3fill in blank

hard

Fix the error in the code by choosing the correct property wrapper for a view model property.

Swift

struct ContentView: View {
    @StateObject var model = Counter()

    var body: some View {
        Text("Value: \(model.[1])")
    }
}

Drag options to blanks, or click blank then click option'

A@State

Bvalue

C@Published

Dvalue.value

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use @Published or @State when accessing the property.

Using nested property names incorrectly.

Access the published property directly by its name without property wrappers in the view body.

4fill in blank

hard

Fill both blanks to declare a published property and update it inside a class.

Swift

class TimerModel: ObservableObject {
    [1] var seconds = 0

    func tick() {
        seconds [2] 1
    }
}

Drag options to blanks, or click blank then click option'

A@Published

B=

C+=

D@State

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '+=' to increment.

Using @State inside a class instead of @Published.

Use @Published to mark the property and '+=' to increment it.

5fill in blank

hard

Fill all three blanks to declare a state variable, update it, and display it in a SwiftUI view.

Swift

struct ClickCounter: View {
    [1] var count = 0

    var body: some View {
        VStack {
            Text("Count: \(count)")
            Button("Increment") {
                count [2] [3] 1
            }
        }
    }
}

Drag options to blanks, or click blank then click option'

A@State

B+

C+=

D@Published

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Published instead of @State in a view.

Using '=' instead of '+=' to update the variable.

Declare count with @State, increment it with '+=' and add 1 with '+'.