@State property wrapper in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a state variable named count initialized to 0.

iOS Swift

@[1] var count = 0

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

AObservedObject

BState

CBinding

DEnvironmentObject

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Binding instead of @State

Forgetting the '@' symbol

Using @ObservedObject for simple state

The @State property wrapper is used to declare a state variable that SwiftUI monitors for changes.

2fill in blank

medium

Complete the code to update the state variable count by incrementing it by 1 inside the button action.

iOS Swift

Button(action: {
    count [1] 1
}) {
    Text("Increment")
}

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A+=

B-=

C*=

D/=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-=' which subtracts instead of adds

Using '*' or '/' operators which multiply or divide

The '+=' operator adds the value on the right to the variable on the left, updating the state.

3fill in blank

hard

Fix the error in the code by completing the declaration of the state variable inside a SwiftUI View struct.

iOS Swift

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

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

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A@State

Bvar

Clet

D@Published

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'var' without @State causes the UI not to update

Using 'let' which is immutable

Using @Published which is for ObservableObject classes

Inside a View struct, state variables must be marked with @State to allow SwiftUI to track changes.

4fill in blank

hard

Fill in the blank to create a button that toggles a Boolean state variable named isOn.

iOS Swift

@State var isOn = false

Button(action: {
    isOn [1] !isOn
}) {
    Text(isOn ? "On" : "Off")
}

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A!=

B==

C=

D+=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' which is a comparison, not assignment

Using '!=' which is a comparison operator

Using '+=' which is for numeric addition

The '=' operator assigns the negated value of isOn back to isOn, toggling the Boolean state.

5fill in blank

hard

Fill the two blanks to declare a state variable count, increment it in a button, and display it in a Text view.

iOS Swift

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

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

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

AState

B+=

CStateObject

DObservedObject

Attempts:

3 left

💡 Hint

Common Mistakes

Using @StateObject or @ObservedObject for simple Int state

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

Forgetting to mark count with @State

Use @State to declare the variable, '+=' to increment it, and display count in Text. @StateObject and @ObservedObject are for classes, not simple state.