swift-closures-mini.md

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default	Swift 4 mini guide: closures	A mini reference guide for closures in Swift 4.	/closures-mini/ /closure-mini/ /block-mini/ /blocks-mini/ /lambda-mini/ /lambdas-mini/

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The mini version of the [closures guide]({{ "/swift-closures" | relative_url }}).

Closure inline

let sorted1 = [4, 30, 7].sorted(by: { (x: Int, y: Int) -> Bool in 
  return x < y 
})
// Equivalent shorter version:
let sorted2 = [4, 30, 7].sorted { $0 < $1 }

Closure as a function parameter

func multiply(x: Int, y: Int, completion: @escaping (Int, Error?) -> Void) {
  completion(x * y, nil)
}
multiply(x: 5, y: 6) { print($1 ?? $0) } // Output: 30

Note: Because this closure is escaping, it could be called even after the function returns.