BuildOptional and buildEither in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is BuildOptional in Swift's result builders?

BuildOptional allows you to include optional parts in a result builder. It helps handle if statements without an else, letting you add code only when a condition is true.

beginner

What does BuildEither do in Swift's result builders?

BuildEither handles if-else or switch statements inside result builders. It chooses between two code paths, building either the first or the second part depending on the condition.

intermediate

How does BuildOptional relate to optional values in Swift?

BuildOptional wraps the optional part of the builder's content in an Optional type. If the optional part is missing, it returns nil, otherwise it returns the built content.

intermediate

Explain the difference between buildEither(first:) and buildEither(second:).

<p><code>buildEither(first:)</code> builds the first branch of a conditional, while <code>buildEither(second:)</code> builds the second branch. They let the builder pick which code to include based on conditions.</p>

beginner

Give a simple example of using BuildOptional in a Swift result builder.

<pre>struct MyBuilder {
  @resultBuilder
  struct Builder {
    static func buildBlock(_ components: String?...) -> String {
      components.compactMap { $0 }.joined(separator: ", ")
    }
    static func buildOptional(_ component: String?) -> String? {
      component
    }
  }

  @Builder
  func build(_ includeExtra: Bool) -> String {
    "Hello"
    if includeExtra {
      "World"
    }
  }
}

let example = MyBuilder().build(true)  // "Hello, World"
let example2 = MyBuilder().build(false) // "Hello"</pre>

What does BuildOptional allow in Swift result builders?

A Including optional code blocks without else

B Handling loops inside builders

C Choosing between two code paths

D Defining variables inside builders

BuildOptional lets you include optional code blocks, like if without else, inside result builders.

Which method handles if-else in result builders?

A buildOptional

B buildBlock

C buildEither

D buildArray

buildEither handles if-else or switch statements by choosing one branch.

What does buildEither(second:) do?

A Builds the first branch of a condition

B Builds the second branch of a condition

C Builds optional content

D Builds an array of components

buildEither(second:) builds the second branch of a conditional statement.

If an optional block is missing, what does buildOptional return?

A nil

B An empty string

C An error

D Zero

buildOptional returns nil if the optional block is missing.

Which of these is true about BuildEither?

A It combines multiple components

B It only works with loops

C It makes code optional

D It chooses between two code paths

BuildEither chooses between two code paths based on conditions.

Explain how BuildOptional works in Swift result builders and when you would use it.

Think about optional parts in your code that may or may not run.

Describe the role of BuildEither in handling conditional branches inside result builders.

Consider how you pick between two options in your code.