The document discusses Core Animation and specifically details the use of CATransaction for managing graphic object animations in iOS applications. It highlights techniques for explicit transactions, disabling actions, and performing animations on layers, including rendering in background contexts. Practical examples are provided to demonstrate the use of CATransaction in application development.

1. CATransaction
What the flush ?!
Amadour Griffais
CocoaHeads Paris
9 janvier 2014

2. Core Animation
• crée et manipule des objets graphiques
• les affiche
• les anime

3. Core Animation

4. Core Animation

5. Core Animation

6. Core Animation

7. Core Animation
Model
Ab
CALayer
CAAnimation

8. Core Animation
Model
Ab
Render server
CALayer
CAAnimation
C++

9. Core Animation
Model
Ab
Render server
CALayer
CAAnimation
C++

10. Core Animation
Model
Ab
CALayer
CAAnimation

11. Core Animation
Model
Ab
CALayer
CAAnimation

12. CATransaction
Core Animation Programming Guide
Explicit Transactions Let You Change Animation Parameters
[CATransaction
[CATransaction
layer.position
[CATransaction
begin];
setAnimationDuration:0.5];
= CGPoint(100,100);
commit];

13. CATransaction
Model
Ab

14. CATransaction
Model
0.5s
Ab

15. CATransaction
Core Animation Programming Guide
Explicit Transactions Let You Change Animation Parameters
[CATransaction
[CATransaction
layer.position
[CATransaction
begin];
setAnimationDuration:0.5];
= CGPoint(100,100);
commit];
Disable Actions Temporarily Using the CATransaction Class
[CATransaction
[CATransaction
layer.position
[CATransaction
begin];
setDisableActions:YES];
= CGPoint(100,100);
commit];

16. CATransaction
Model
Ab

17. CATransaction
Model
Ab

18. CATransaction Class Reference

19. CATransaction Class Reference

20. Model
Render server

21. Model
Ab
Render server

22. [CATransaction flush];
Model
Ab
Render server

23. [CATransaction flush];
Model
Ab
Render server
Ab

24. [CATransaction flush];
• Commit de la transaction implicite
• Englobe toutes les transaction explicites
• Envoie les modifications au render server

25. [CATransaction flush];
• A chaque tour de runloop
• Provoque layout si nécessaire

27. [CATransaction flush];
• A chaque tour de runloop
• Provoque layout si nécessaire
• Provoque display si nécessaire

29. [CATransaction flush];
• Equivalent à [CATransaction commit];
• Attend la fin des transaction explicites
• Définit le beginTime des animations !

30. [CATransaction begin];
[CATransaction setAnimationDuration:0.5];
CAAnimation* anim = [CABasicAnimation animationWithKeyPath:@"opacity"];
[layer addAnimation:anim forKey:@"opacity"];
//<CABasicAnimation:0xc028980; duration = 0.5; keyPath = opacity>
[CATransaction commit];
//<CABasicAnimation:0xc028980; duration = 0.5; keyPath = opacity>
[CATransaction flush];
//<CABasicAnimation:0xc028980; beginTimeMode = absolute;
//
beginTime = 11797.4; duration = 0.5; keyPath = opacity>

31. En pratique
Déclencher une animation d’attente avant de
bloquer le main thread
[activityIndicator startAnimating];
[self doReallyLongStuff];

32. En pratique
Déclencher une animation d’attente avant de
bloquer le main thread
[activityIndicator startAnimating];
[CATransaction flush];
[self doReallyLongStuff];

33. En pratique
Appliquer des animations implicites à des
layers qui viennent d’être ajoutés
CALayer* layer = [CALayer layer];
layer.frame = CGRectMake(0, 0, 200, 200);
layer.backgroundColor = [[UIColor redColor] CGColor];
[self.view.layer addSublayer:layer];
layer.frame = CGRectMake(100, 100, 200, 200);

34. En pratique
Appliquer des animations implicites à des
layers qui viennent d’être ajoutés
CALayer* layer = [CALayer layer];
layer.frame = CGRectMake(0, 0, 200, 200);
layer.backgroundColor = [[UIColor redColor] CGColor];
[self.view.layer addSublayer:layer];
[CATransaction flush];
layer.frame = CGRectMake(100, 100, 200, 200);

35. En pratique
Faire un rendu dans un contexte en
background et nettoyer derrière soi
CALayer* layer = ...;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
^{
UIGraphicsBeginImageContext(layer.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[layer renderInContext:context];
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_sync(dispatch_get_main_queue(), ^{
[self useImage:image];
});
});

36. En pratique
Faire un rendu dans un contexte en
background et nettoyer derrière soi
CALayer* layer = ...;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
^{
UIGraphicsBeginImageContext(layer.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[layer renderInContext:context];
[CATransaction flush];
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_sync(dispatch_get_main_queue(), ^{
[self useImage:image];
});
});

37. En pratique ?
Faire un rendu dans un contexte en
background et nettoyer derrière soi
CALayer* layer = ...;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
^{
[CATransaction lock];
UIGraphicsBeginImageContext(layer.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[layer renderInContext:context];
[CATransaction unlock];
[CATransaction flush];
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_sync(dispatch_get_main_queue(), ^{
[self useImage:image];
});
});

38. Questions ?
• Ressources
• WWDC videos
• Core Animation Programming Guide
@amadour