SwiftUI Test 2

Question 1

What will the numbers constant contain when this code is run?

Accepted Answer

[[1,1],[2,1],[3,1]]

Answer

The outer `map` iterates through `outer` values from 1 to 3. For each `outer`, the inner `map` iterates `inner` only once, always assigning `1`. The closure `[outer, inner]` then creates a two-element array for each iteration. The outer `map` collects these individual `[outer, inner]` arrays, resulting in `[1,1]`, `[2,1]`, and `[3,1]` sequentially, which are then combined into the final array `[[1,1],[2,1],[3,1]]`.

Question 2

Integers are stored in how many bits?

Accepted Answer

It depends on the device

Answer

In Swift, the default `Int` type is platform-dependent, meaning its storage size varies based on the device's architecture. On a 32-bit platform, `Int` is 32-bit, while on a 64-bit platform, `Int` is 64-bit. This design allows `Int` to be optimized for the native word size of the device, making its storage size variable rather than fixed.

Question 3

What will the code below yield as a result?

Accepted Answer

1, 5, 9, 13

Answer

The `stride(from:to:by:)` function generates a sequence of values starting from the `from` value, incrementing by the `by` value, and stopping *before* reaching the `to` value. Starting at 1 and incrementing by 4, the sequence is 1, 5, 9, 13. The next value, 17, is not included because the stride stops *before* 17.

Question 4

Which of the following methods for creating a raw string in Swift is correct?

Accepted Answer

#"Hello, World!"#

Answer

Swift 5 introduced raw strings, which are created by enclosing the string literal within one or more hash symbols (`#`). This syntax, like `"#Hello, World!#"`, allows backslashes and other special characters within the string to be treated as literal text rather than escape sequences. This is particularly useful for regular expressions or file paths where escaping many characters would be cumbersome.

Question 5

What data type will be allocated to result in the code below?

Accepted Answer

Tuple

Answer

In Swift, a tuple is a compound data type that groups multiple values into a single, ordered collection. The code `let result = (true, "hello", 10)` creates a tuple because it combines values of different types (`Bool`, `String`, `Int`) within parentheses. The `result` constant will therefore be allocated as a tuple of type `(Bool, String, Int)`.

SwiftUI Practice Test

SwiftUI Practice Test

SwiftUI Test 2