Weak, Strong, Unowned - Hector Matos

Transcript

1. Weak, Strong, Unowned Oh, My!

2. Quick Intro

3. Hi! I'm Hector Matos

4. None

5. Sr. Software Engineer @ Capital One

6. @allonsykraken on the Twitters

7. Father of KrakenDev.io

8. ARC

9. - (void)releaseTheKraken { Kraken *kraken = [[Kraken alloc] init]; //+1

   retain [kraken release]; //generated by ARC }

10. Magic has it's limitations And so does ARC

11. Leaked Memory & Retain Cycles

12. None
13. None

14. Strong References Default in Swift

15. Now Stop, Example Time //Kraken holds a strong reference to

    the yummy human. class Kraken { var yummyHuman: Human }

16. // The animation closure holds a strong reference to self

    // self.retainCount is 1 here UIView.animateWithDuration(0.3) { // self.retainCount is 2 here self.view.alpha = 0.0 }

17. Questions?

18. Weak References Safe - Independent

19. Stop, Collaborate, & Listen! (to my next example) class KrakensFace:

    UIView { @IBOutlet weak var razorSharpTeeth: UIView! } KrakenAPI.eat(yummyHuman, whenFinished: { [weak self] in self?.waitForNextMealTime() })

20. WTF is "[weak self] in"?!

21. Capture Lists It's just an array. That's all it is.

    There, there. It's all over now. !

22. KrakenAPI.eat(yummyHuman, finished: { [weak self, unowned lovedOne = yummyHuman.lovedOne] in

    self?.waitForNextMealTime() })

23. Questions?

24. Unowned References Mutual Dependence

25. class Human { var heart: ! func seeKrakenComing() { heart.haveHeartAttack()

    } } class !: Organ { unowned let human: Human init(human: Human) { self.human = human } func haveHeartAttack() { human.die() } } let human = Human() human.heart = !(human: human)

26. Questions?

27. None

28. ❤