Which of the following is a correct way to declare a closure that takes an Int and returns its square?

easy📝 Conceptual Q2 of 15

iOS Swift - Swift Language Essentials

Alet square = (num: Int) -> Int { num * num }

Blet square = { (num: Int) -> Int in return num * num }

Cfunc square(num: Int) -> Int { num * num }

Dlet square = Int -> Int { return num * num }

Step-by-Step Solution

Solution:

Step 1: Review closure syntax
A closure uses curly braces with parameters and return type inside, followed by 'in' keyword.
Step 2: Match the correct syntax
let square = { (num: Int) -> Int in return num * num } matches the closure syntax: parameters, return type, 'in', and body.
Final Answer:
let square = { (num: Int) -> Int in return num * num } -> Option B
Quick Check:
Closure syntax = let square = { (num: Int) -> Int in return num * num } [OK]

Quick Trick: Closures use braces and 'in' keyword before code [OK]

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