The document discusses whether Swift is ready for production use. It notes that Swift is growing in popularity and stability according to language indexes. Swift 1.2 includes improvements like faster builds and better compiler diagnostics. A new app was written in Swift for Duolingo in 3 months, and it had a low crash rate despite tooling issues. While interfacing with Objective-C and compiler bugs are still problems, the document concludes that Swift is ready for new code due to its type safety and architecture benefits. Learning functional patterns and dealing with strict typing are identified as challenges to using Swift.

2. @wolfgang_damm
Wolfgang Damm
CTO & Co-Founder
wolfgang@pocket-lifestyle.com
www.pocket-lifestyle.com

3. Swift
Should I use it for production?

4. Current State
• TIOBE Index of language popularity
• Swift #27, increasing
• Objective-C #4, declining
• Github number of active repositories
• Swift #18, growing
• Objective-C #11, flat
Data as of February 2015
http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html
http://githut.info/

5. Swift 1.2
• Xcode 6.3 Beta
• Faster builds & executables
• Better compiler diagnostics
• Stability
• and changes to the language!

6. as! for failable casts

7. if let a = a, b = b, c = c {

8. Nullability Annotations

9. enums export to
Objective-C

10. Deferred initialisation
of let constants

11. Set

12. So is it ready for prime
time?

13. Duolingo Test Center
• New App written in Swift
• 3 month
(1 dev, design/backend inplace)
+ Value types, custom operators
+ Stronger, static type system, with
type inference
+ Generics especially for typesafe
collections

14. Duolingo Test Center
- Tooling: Xcode, crashes, very slow code
completion, basically no debugger, unstable/
unreliable syntax highlighting (got better)
- Swift language changes.
Known from the beginning, in retrospect only
little time spent on keeping source up to date
- Incomprehensible compiler errors

15. Duolingo Test Center
• Crash rate ~0.2% (crashes/downloads)
mostly in Objective-C third party library
• Swift eased process of building a solid
architecture. Eliminating classes of bugs by
design (e.g. Swift’s type system)

16. @brentsimmons
ObjC: “I am laughing out loud”
Swift: "LOL"

17. @brentsimmons
• Harder on 2nd look
• optionals, generics, and tuples, value vs reference
• functional design patterns
• strict type safety
• issue interoperation with Objective-C
• “Swift is happening.”

18. Random Thoughts from
Developers
• Common internal libraries, not rewriting just to
be Swift
• Sometimes interacting with Cocoa API’s harder
than thought
• Strict typing is a killer feature (finds bugs during
compile time)

19. So is it ready for prime
time?

20. Yes it is!

21. Our take aways
• Future of iOS will be Swift
• New code written in Swift
• Rewriting only were it makes sense (lot of code changes,
restructuring)
• Know Swift AND Objective-C
• Swift uses different patterns
• Hard to follow good patterns when interfacing with
Objective-C

22. Experience

23. Experience
• Compiler bugs: crashes instead of error
• Renew Certificate, otherwise it crashes submitted
build
• At first slower when writing code, but learning fast
• Choice between Objective-C vs Swift patterns
• Cocoapods support is still beta
• cocoapods --pre installs 1.0.36(beta)

24. pod 'Alamofire', :git => 'https://github.com/Alamofire/
Alamofire.git', :branch => ‘xcode-6.3'
pod 'SwiftyJSON', :git => 'https://github.com/
SwiftyJSON/SwiftyJSON.git', :branch => 'xcode6.3'

25. Favourite Swift Way
enum Router: URLStringConvertible {
static let baseURLString = "http://example.com"
case Root
case User(String)
case Post(Int, Int, String)
// MARK: URLStringConvertible
var URLString: String {
let path: String = {
switch self {
case .Root:
return "/"
case .User(let username):
return "/users/(username)"
case .Post(let year, let month, let title):
let slug = title.stringByReplacingOccurrencesOfString(" ", withString: "-").lowercaseString
return "/(year)/(month)/(slug)"
}
}()
return Router.baseURLString + path
}
}
Enum with associated value and computed property

26. Learn Swift
• Read “The Swift Programming Language” by Apple
• thatthinginswift.com
• swiftdoc.org
• learnswift.tips
• Start coding in Swift!
• github.com/raywenderlich/swift-style-guide

27. My experience learning
Swift
• Functional Programming is different
• Force yourself to using good practices. Make
use of strict types. Which is hard.
• Harder to define public interface (no header).
Standard access modifier is internal. Also makes
testing harder.

28. Single most hardest
thing in Swift?

29. ;

31. @wolfgang_damm
Wolfgang Damm
CTO & Co-Founder
wolfgang@pocket-lifestyle.com
www.pocket-lifestyle.com