Swift@IBM and Swift 3

1. What’s new in Swift 3?
Pushkar N Kulkarni | @pushkar_nk | pushkarnk
IBM Runtimes
IBM India Software Lab

2. Agenda
• Swift@IBM - a server-side effort
• Language changes in Swift 3.0 (hands-on)
• Swift Package Manager (hands-on)

3. Swift@IBM
• Swift on Linux – swift.org
• IBM Swift Package Catalog
• Kitura
• IBM Swift Sandbox
Blog: https://developer.ibm.com/swift/blogs/

4. Swift on Linux

5. IBM Swift Package Catalog
• https://swiftpkgs.ng.bluemix.net/
• Find, explore and share packages
from the open-source Swift
ecosystem
• Explore dependencies
• Submit your own packages
5

6. Kitura Web Framework
What is it?
• New, modular, package-based web framework
written in Swift
Why is this cool?
• Empower a new generation of native mobile
developers to write and deploy code into the
Cloud.
Developer Benefits ?
• Delivers core technologies needed to
stand up enterprise apps on the server
• Enables developers to create a web
application in Swift and deploy these
servers on Linux and the Cloud.
http://github.com/ibm-swift/kitura 6

7. IBM Swift Sandbox
• Interactive sandbox for
rapid prototyping and
experimentation in Swift
• Saves your work
• Supports multiple
versions of Swift
• Responsive design
7
https://swiftlang.ng.bluemix.net/

8. Swift 3.0
• Major release
• Not source-compatible with Swift 2.2
• Fundamental changes to the language and standard library
• Swift package manager – Linux & Darwin

9. Language changes
• Removal of C-style for-loops
• Removal of increment/decrement operators
• New function to find first element passing a predicate
• Consistent label behavior for first parameter

10. Language changes
• New API guidelines
• Keywords in member references
• Case labels with multiple patterns
• Generic type-aliasing

11. C-Style code (Swift 2.2)
func arithmeticSeries(a: Int, d: Int, n: Int) -> [Int] {
var series: [Int] = []
for var i = 0; i < n; i++ {
series += [a + i*d]
}
return series
}
arithmeticSeries(1, d: 3, n: 10)

12. C-style constructs removed
//this works on all Swift versions
func arithmeticSeries(a: Int, d: Int, n: Int) -> [Int] {
var series: [Int] = []
for i in 0..<n {
series += [a+i*d]
}
return series
}
print(arithmeticSeries(1, d: 3, n: 10))

13. Sequence iteration - stdlib
func arithmeticSeries(a: Int, d: Int, n: Int) -> [Int] {
var series: [Int] = []
for x in sequence(first: a, next: {$0+d}).prefix(n){
series += [x]
}
return series
}
print(arithmeticSeries(a: 1, d: 3, n: 10))

14. Sequence.first(where:)
Finding the first element that satisfies a predicate
let series = arithmeticSeries(a: 1, d: 3, n: 10)
//first double digit element
series.first(where: {$0 > 9})

15. Consistent label behavior for first parameter
Until Swift 2.2
func sum (x a: Int, y b: Int, z c: Int) -> Int {
return a + b + c
}
>> sum (x: 10, y: 20, z: 30)

16. Consistent label behavior for first parameter
Until Swift 2.2
func sum (a: Int, y b: Int, z c: Int) -> Int {
return a + b + c
}
>> sum (10, y: 20, z: 30)

17. Consistent label behavior for first parameter
Until Swift 2.2
func sum (a: Int, b: Int, c: Int) -> Int {
return a + b + c
}
>> sum (10, b: 20, c: 30)

18. Consistent label behavior for first parameter
In Swift 3.0
func sum (a: Int, b: Int, c: Int) -> Int {
return a + b + c
}
>> sum (a: 10, b: 20, c: 30)

19. Consistent label behavior for first parameter
In Swift 3.0 – to save your clients/users from doing extra work
func sum (_ a: Int, b: Int, c: Int) -> Int {
return a + b + c
}
>> sum (10, b: 20, c: 30)

20. Power of Enums
public enum Video {
case Public(Int, Int, String)
case Private(String)
case Optional(String, Int)
}

21. Power of Enums
public enum Video {
case Public(Int, Int, String)
case Private(String)
case Optional(String, Int)
}

22. Power of Enums
extension Video {
func getName() -> String {
switch self {
case let .Public(_, _, s) :
return s
case let .Private(s):
return s
case let .Optional(s, _):
return s
}
}
}

23. Lower camel case – New API guideline
public enum Video {
case public(Int, Int, String)
case private(String)
case optional(String, Int)
}
public enum Video {
case `public`(Int, Int, String)
case `private`(String)
case `optional`(String, Int)
}

24. Keywords in member references
extension Video {
func getName() -> String {
switch self {
case let .public(_, _, s) :
return s
case let .private(s):
return s
case let .optional(s, _):
return s
}
}
}
//backticks not needed while referencing member!

25. Case labels with multiple patterns
extension Video {
func getName() -> String {
switch self {
case let .public(_, _, s),
let .private(s),
let .optional(s, _):
return s
}
}
}

26. Reversing a triplet
func reverse(t: (Int, Int, Int)) -> (Int, Int, Int) {
return (t.2, t.1, t.0)
}
reverse(t: (1,2,3))
func reverse(t: (Double, Double, Double)) -> (Double,
Double, Double) {
return (t.2, t.1, t.0)
}
reverse(t: (1.1, 2.3, 3.1))

27. Reversing a triplet
typealias IntTriplet = (Int, Int, Int)
typealias DoubleTriplet = (Double, Double, Double)
func reverse(t: IntTriplet) -> IntTriplet {
return (t.2, t.1, t.0)
}
func reverse(t: DoubleTriplet) -> DoubleTriplet {
return (t.2, t.1, t.0)
}

28. Generic Typealiases
typealias Triplet<T> = (T, T, T)
func reverse<T>(t: Triplet<T>) -> Triplet<T> {
return (t.2, t.1, t.0)
}
reverse(t: (1,2,3)
reverse(t: (1.1,2.2,3.2)

29. Generic Type aliases
Will your function reverse function reverse (“swift”, 3.14, 100) ?
How would you do that?

30. Swift Package Manager
A successful modern language needs an efficient package manager
• A tool for managing distribution of Swift code
• Integrated with the Swift build system
• Downloading, compiling and linking dependencies
• Baby step towards matching CocoaPods & Carthage

31. Swift Package Manager
• Modules
• Packages
Manifest file
Git based for now
• Products
Library or executable
• Dependencies
Semantic version management

32. Package.swift
import PackageDescription
let package = Package(
name: ”Reverser",
targets: [],
dependencies: [
.Package(url: "https://github.com/apple/example-package.git",
majorVersion: 1),
]
)

33. Thank you!
Twitter - @pushkar_nk
GitHub - pushkarnk