SwiftUI uses result builders - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this SwiftUI View code?

Consider this SwiftUI view using a result builder to create a VStack. What text will be shown on the screen?

Swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack {
            Text("Hello")
            Text("World")
        }
    }
}

// Assume this is run in a SwiftUI preview or app

A A vertical stack showing two lines: "Hello" on top and "World" below

B A horizontal stack showing "Hello World" on the same line

C An empty view with no text displayed

D A runtime error because VStack requires explicit closure syntax

💡 Hint

Think about what VStack does and how result builders let you list views inside it.

VStack arranges views vertically. The result builder lets you list multiple views inside the closure, so Text("Hello") and Text("World") appear stacked vertically.

🧠 Conceptual

intermediate

What role do result builders play in SwiftUI?

Which statement best describes how SwiftUI uses result builders?

A They replace the need for any closures in SwiftUI

B They automatically generate UI code from JSON data

C They are used to handle asynchronous network calls in SwiftUI

D They allow writing multiple views inside a closure that are combined into one view container

💡 Hint

Think about how SwiftUI lets you list views inside containers like VStack.

Result builders let you write multiple child views inside a closure, and SwiftUI combines them into a single container view like VStack or HStack.

🔧 Debug

advanced

Why does this SwiftUI code cause a compile error?

Examine this SwiftUI code snippet. Why does it fail to compile?

Swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack {
            if true {
                Text("Visible")
            } else {
            }
            Text("Always here")
        }
    }
}

A Because the else block is missing a return statement

B Because the if-else inside VStack is not allowed without an explicit return type in result builders

C Because Text views must be wrapped in Group when used conditionally

D Because VStack cannot contain conditional statements

💡 Hint

Think about how result builders handle conditional branches inside view containers.

SwiftUI's result builder requires all branches of an if-else to produce the same type. Without explicit typing or using Group, the compiler cannot infer the combined type, causing an error.

📝 Syntax

advanced

Which option correctly uses a result builder in SwiftUI?

Choose the code snippet that correctly uses a result builder to create a view with two Text elements.

A VStack { Text("One") ; Text("Two") }

B VStack { Text("One") Text("Two") ; }

C VStack { Text("One") Text("Two") }

D VStack { Text("One") , Text("Two") }

💡 Hint

Remember how Swift separates statements inside closures.

In Swift closures, statements must be separated by semicolons or newlines. Option A correctly separates the two Text views with a semicolon.

🚀 Application

expert

How many views are created by this SwiftUI code using result builders?

Given this SwiftUI code, how many Text views will be created and displayed?

Swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack {
            ForEach(0..<3) { i in
                if i % 2 == 0 {
                    Text("Even: \(i)")
                } else {
                    Text("Odd: \(i)")
                }
            }
        }
    }
}

A 2

B 1

C 3

D 0

💡 Hint

Count how many times the loop runs and what views it creates each time.

The ForEach runs 3 times (0,1,2). Each iteration creates one Text view, so total 3 Text views are created.