Slides from 22nd CocoaHeads São Paulo @ Elo7

1. What’s new in Swift 3
22nd CocoaHeads SP @ Elo7 - Marcio Klepacz
@marciok

2. Agenda
• Introduction
• Where to find Swift 3
• A Swift more “Swifty”
• New Foundation Value Types
• Safety Increased
• Coolness with SPM
• Conclusion

3. Introduction
or what to expect from Swift 3

4. Swift 3
• Was also brought by proposals from the
community.
• Is focused on clarity, at the point of use.
• Brings more clarity when working with legacy
APIs
• Safer

5. Where to find Swift 3

6. Where to find Swift 3
• Xcode 8 (Beta)
• swift.org snapshots

7. Considerations
• You can only submit apps using Swift 3 when
Xcode GM is shipped ~end of 2016.
• Swift 3 changes everything. Xcode 8 comes
with a code migration tool (can migrate to 2.3).
However, I would still check the migrations made
by Xcode.

8. A Swift more “Swifty”

9. Swift more “Swifty”
• Not terse or Verbose code.
• Clarity is more important than brevity.
• Concise code is a consequence of using
contextual cues.
• What they mean (In my option) is: Let’s ditch
legacy ObjC API designs, and be more “Swifty”.

10. Before:
After:
NSTimer.scheduledTimerWithTimeInterval(0.35, target: self, …)
NSTimer.scheduledTimer(timeInterval: 0.35, target: self, …)
UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
UIFont.preferredFont(forTextStyle: UIFontTextStyleSubheadline)
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView?
func viewForZooming(in scrollView: UIScrollView) -> UIView?
Swift 2
Swift 3

11. Before:
After:
func findCocoaheads(in city: String) {
//...
}
findCocoaheads(in:"São Paulo")
func findCocoaheadsIn(city: String) {
//...
}
findCocoaheadsIn("São Paulo")
Swift 2
Swift 3

12. Before:
After:
UIColor.blueColor()
UIColor.blue() // or simply .blue() if the compile can infer
cocoaheads(insert: “São Paulo” atIndex: 0)
cocoaheads(insert: “São Paulo” at: 0)
NSUserDefaults.standardUserDefaults()
UserDefaults.standard() // NSUserDefaults was renamed to UserDefaults
Swift 2
Swift 3
Omitting needless words

13. New Foundation Value
Types

14. New Foundation value types

15. Example
let dateComponent = NSDateComponents()
dateComponent.year = 2016
let anotherComponent = dateComponent
anotherComponent.year = 2017 //`dateComponent` year was also changed to 2017
var dateComponent = DateComponents()
dateComponent.year = 2016 // It will warn you if `dateComponent` is a `let`
let anotherComponent = dateComponent
anotherComponent.year = 2017 //`dateComponent` is still 2016
Before:
Swift 2
After: Swift 3

16. Safety Increased

17. Safety Increased
Before:
After:
var cocoaheads = [String!]()
cocoaheads.append("São Paulo")
let sp = cocoaheads[0]
sp.dynamicType // ImplicitlyUnwrappedOptional<String>
Swift 2
Swift 3
var cocoaheads = [String!]()
cocoaheads.append("São Paulo")
let sp = cocoaheads[0]
sp.dynamicType // Optional<String>
let dangerousSp: String! = cocoaheads[0]
dangerousSp.dynamicType // ImplicitlyUnwrappedOptional<String>
No more `ImplicitlyUnwrappedOptional` propagation

18. Coolness with SPM

19. Coolness with SPM
• The ability to pass custom flags during linker
invocations. Also on C and Swift compilation.
• Export as dynamic library
==
• Easy to Interoperate with other languages

20. Coolness with SPM
• Examples:
• SwiftyRuby - Calling Ruby from Swift
• SwiftyJava - Calling Java from Swift

21. Conclusion

22. Conclusion
• Swift 3 changes everything (again). It will force
us get rid of our ObjC muscle muscle memory.
• Was also brought by the community. We can
always go on Github to complain, suggest and
change.
• There are many others news things that weren’t
mentioned at this presentation, so don’t forget to
check online for other things.

23. Thanks!
• Twitter: @marciok
• Github: /marciok
• References:
• https://www.raywenderlich.com/135655/whats-new-
swift-3
• https://www.bignerdranch.com/blog/wwdc-2016-
increased-safety-in-swift-3/
• https://developer.apple.com/videos/play/wwdc2016/402/