Fizz Buzz in Swift - Speaker Deck

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FizzBuzz in Swift Abizer Nasir | @abizern | abizern.org Geek, Raconteur, Jobseeker

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The Set Up You’ve turned up for an interview…

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FizzBuzz • For some set of input numbers: • If the number is a multiple of 3 print “Fizz” • If the number is a multiple of 5 print “Buzz” • If the number is a multiple of 3 and 5 print “FizzBuzz” • Otherwise, Print the number.

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Demo

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Simple Implementation func fizzBuzz (number: Int) -> String { var output = "" ! if number % 3 == 0 { output += "Fizz" } ! if number % 5 == 0 { output += "Buzz" } ! if output.isEmpty { output = "\(number)" } return output }

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Pattern Matching func fizzBuzz (number: Int) -> String { switch (number % 5, number % 3) { case (0, 0): return "FizzBuzz" case (0, _): return "Buzz" case (_, 0): return "Fizz" default: return "\(number)" } }

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FizzBuzzBar • Same as FizzBuzz, except • For multiples of 7 add the string “Bar” • e.g. 105 -> “FizzBuzzBar”

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Simple solution func fizzBuzzBar(number: Int) -> String { switch (number % 7, number % 5, number % 3) { case (0, 0, 0): return "FizzBuzzBar" case (0, 0, _): return "BuzzBar" case (_, 0, 0): return "FizzBuzz" case (0, _, 0): return "FizzBar" case (0, _, _): return "Bar" case (_, 0, _): return "Buzz" case (_, _, 0): return "Fizz" default: return "\(number)" }

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Pass Options func fizzBuzzBar(number: Int, #options: Array<(Int, String)>) -> String { var output = "" for (divisor, description) in options { if number % divisor == 0 { output += description } } ! if output.isEmpty { output = "\(number)" } ! return output }

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for i in 1...105 { let options = [(3, "Fizz"), (5, "Buzz"), (7, "Bar")] println(fizzBuzzBar(i, options: options)) }

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Extension extension Int { func fizzBuzzBar(options: Array<(Int, String)>) -> String { var output = "" for (divisor, description) in options { if self % divisor == 0 { output += description } } ! if output.isEmpty { output = "\(self)" } return output } }

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for i in 1...105 { let options = [(3, "Fizz"), (5, "Buzz"), (7, "Bar")] println(i.fizzBuzzBar(options)) }

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Protocol protocol FizzBuzzable { func fizzBuzz(options: Array<(Int, String)>) -> String }

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extension Int: FizzBuzzable { func fizzBuzzBar(options: Array<(Int, String)>) -> String { var output = "" for (divisor, description) in options { if self % divisor == 0 { output += description } } ! if output.isEmpty { output = "\(self)" } return output } }

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But what if they change to strings?

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FizzBuzz with Strings • For a list of strings: • If the string contains the word “Three” print “Fizz” • If the string contains the word “Five” print “Buzz” • If the string contains the words “Three” and “Five” print “FizzBuzz”

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let stringInput = ["one", "three", "ThreeFive", "EleventyOne"] for string in stringInput { var result = "" ! if string.rangeOfString("three", options: .CaseInsensitiveSearch) { result += "Fizz" } ! if string.rangeOfString("five", options: .CaseInsensitiveSearch) { result += "Buzz" } ! if result.isEmpty { result = string } ! println(result) }

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Generic Protocol protocol FizzBuzzable { typealias ItemType func fizzBuzz(options: Array<(ItemType, String)>) -> String }

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extension Int: FizzBuzzable { typealias ItemType = Int func fizzBuzz(options: Array<(Int, String)>) -> String { var output = "" for (divisor, description) in options { if self % divisor == 0 { output += description } } ! if output.isEmpty { output = "\(self)" } ! return output } }

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extension String: FizzBuzzable { typealias ItemType = String func fizzBuzz(options: Array<(String, String)>) -> String { var output = "" for (substring, description) in options { if self.rangeOfString(substring, options: .CaseInsensitiveSearch) { output += description } ! if output.isEmpty { output = self } ! return output } }

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for x in 1..20 { let options = [(3, "Fizz"), (5, "Buzz")]; println(x.fizzBuzz(options)) } ! for x in ["three", "six", "ninetyfive"] { let options = [("three", "Fizz"), ("five", "Buzz")] println(x.fizzBuzz(options)) }

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So now we can use a typed array

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let typedArray: FizzBuzzable[] = [1, 3, 5, 15, "three", "five", "wibble"]

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for x in typedArray { let intOptions = [(3, "Fizz"), (5, "Buzz")] let strOptions = [("three", "Fizz"), ("five", "Buzz")] var output = "" ! if let num = x as? Int { output = num.fizzBuzz(intOptions) } else if let str = x as? String { output = str.fizzBuzz(strOptions) } ! println(output) }

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Don’t try to do things the same way as you did in Objective-C

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Think of types and interfaces rather than classes and methods

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Learn a functional programming language

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fizzBuzz :: Integer -> String fizzBuzz n | n `mod` 15 == 0 = "FizzBuzz" | n `mod` 5 == 0 = "Fizz" | n `mod` 3 == 0 = "Buzz" | otherwise = show n

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fizzBuzz :: Integer -> String fizzBuzz n | n `mod` 15 == 0 = "FizzBuzz" | n `mod` 5 == 0 = "Fizz" | n `mod` 3 == 0 = "Buzz" | otherwise = show n func fizzBuzz (number: Int) -> String { if number % 15 == 0 { return “FizzBuzz” } else if number % 5 == 0 { return "Buzz" } else if number % 3 == 0 { return "Fizz" } else { return “\(number)” } }

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• http://learnyouahaskell.com • http://book.realworldhaskell.org

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Write the code, change the world.

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Find the bugs, ﬁle the radars

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“We have every opportunity and every encouragement before us, to form the noblest purest constitution on the face of the earth. We have it in our power to begin the world over again” Thomas Paine, Common Sense, 1776

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Thank You Abizer Nasir | @abizern | abizern.org Geek, Raconteur, Jobseeker