Why advanced patterns create premium apps in iOS Swift - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a SwiftUI view struct.

iOS Swift

struct ContentView: [1] {
  var body: some View {
    Text("Hello, world!")
  }
}

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

AView

BUIViewController

CAppDelegate

DSceneDelegate

Attempts:

3 left

💡 Hint

Common Mistakes

Using UIKit classes like UIViewController instead of SwiftUI View.

In SwiftUI, views are structs that conform to the View protocol.

2fill in blank

medium

Complete the code to create a state variable in SwiftUI.

iOS Swift

@[1] private var count = 0

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AEnvironmentObject

BState

CObservedObject

DBinding

Attempts:

3 left

💡 Hint

Common Mistakes

Using @ObservedObject or @Binding when a simple state is needed.

The @State property wrapper is used to declare a state variable in SwiftUI.

3fill in blank

hard

Fix the error in the code by completing the missing protocol conformance.

iOS Swift

class DataModel: [1] {
  @Published var name = ""
}

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ACodable

BIdentifiable

CObservableObject

DEquatable

Attempts:

3 left

💡 Hint

Common Mistakes

Using Identifiable or Codable which do not support @Published.

To use @Published properties, the class must conform to ObservableObject.

4fill in blank

hard

Fill both blanks to create a computed property that filters an array.

iOS Swift

var filteredItems: [String] {
  items.filter { $0.[1]([2]) }
}

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Acontains

B"a"

C"b"

Dstarts(with)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'starts(with)' with wrong substring or missing quotes.

The filter method uses a closure that returns true for items containing the letter "a".

5fill in blank

hard

Fill all three blanks to filter a dictionary for positive values.

iOS Swift

let positiveScores = scores.filter { [1], [2] in [2] [3] 0 }

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Aplayer

Bscore

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for filtering positive scores.

This dictionary filter keeps players with scores greater than zero.