Writing Safer Code With Swift

SWIFTWRITING SAFER CODE WITH

WRITING SAFER CODE WITH SWIFT

OVERVIEW▸ What Is Swift?▸ Basic Syntax▸ Why Do We Need Safety?▸ How Can Swift Help?

WHAT IS SWIFT?

WHAT IS SWIFT?

▸ General-purpose, multi-paradigm, programming language▸ Object oriented programming▸ Functional programming▸ Imperative programming

▸ Open source as of December 2015▸ Designed by Apple

A PROGRAMMING LANGUAGE

WHAT IS SWIFT?

NOT JUST APPLE DEVICES▸ Web development

▸ Kitura▸ Official linux binaries▸ Swift For Windows

WHAT IS SWIFT?

BASIC SYNTAXlet hello = "Hello, World!"

WHAT IS SWIFT?

BASIC SYNTAXstruct Hello {

let name: String func message() -> String { return "Hello, \(self.name)!” }}

let helloSFDevs = Hello(name: "SF Devs")

helloSFDevs.message()

WHAT IS SWIFT?

BASIC SYNTAXlet temperatureInFahrenheit = 40

if temperatureInFahrenheit <= 32 { print("It's very cold. Consider wearing a scarf.") } else { print("It's not that cold. Wear a t-shirt.") }

WHAT IS SWIFT?

BASIC SYNTAXfor index in 1...5 { print("\(index) times 5 is \(index * 5)") }

let names = ["Anna", "Alex", "Brian", "Jack"]

for name in names { print("Hello, \(name)!") }

WHAT IS SWIFT?

OTHER BASIC STUFF▸ switch, guard▸ while, repeat-while▸ guard▸ enum, var▸ exception throwing/catching▸ closures (AKA lambdas, anonymous functions)

WHY DO WE NEED SAFETY?

WHY DO WE NEED SAFETY?

TO PROTECT YOURSELF…▸ Spec changes

▸ Brittle code

▸ Bugs

▸ Runtime errors

▸ Null Reference Exceptions

▸ Parsing errors

▸ We want to minimize these these things

WHY DO WE NEED SAFETY?

…FROM YOURSELF

HOW CAN SWIFT HELP?

HOW CAN SWIFT HELP?

▸ let vs. var▸ higher order functions▸ ? operator▸ if let▸ guard

HOW CAN SWIFT HELP?

LET VS. VAR

HOW CAN SWIFT HELP?

HIGHER ORDER FUNCTIONS

HOW CAN SWIFT HELP?

? OPERATOR

OTHER COOL STUFF

PRODUCTION JSON PARSINGguard

let id = json["Id"] as? Int, let lotId = json["LotId"] as? Int, let customerJson = json["Customer"] as? NSDictionary, let vehiclesJson = json["Vehicles"] as? [NSDictionary], let createdBy = json["CreatedBy"] as? String, let createdOnStr = json["CreatedOn"] as? String, let modifiedOnStr = json["ModifiedOn"] as? String else { return Result.Failure("Could not parse purchase json: \(json)")} guard let createdOn = toNSDate(.ISO8601, dateString: createdOnStr) else { return Result.Failure("Could not parse createdOn date: \(createdOnStr)")} guard let modifiedOn = toNSDate(.ISO8601, dateString: modifiedOnStr) else { return Result.Failure("Could not parse modifiedOn date: \(modifiedOnStr)")}

OTHER COOL STUFF

ARGO▸ https://github.com/thoughtbot/Argo

WRITING SAFER CODE WITH SWIFT

LEARN MORE▸ Official Documentation

▸ https://developer.apple.com/library/ios/documentation/Swift

▸ https://www.raywenderlich.com/▸ https://realm.io/news/swift-summit/

WRITING SAFER CODE WITH SWIFT

ANY QUESTIONS?