Memory Management

Lightening talk done at NSLondon about Memory Management. Covering many of the common mistakes people have with memory management using ARC and how to avoid. Briefly covering the runtime support for ARC.

Related blog post: http://kylefuller.co.uk/posts/memory-management-arc/

Transcript

1. Memory Management
2. -[NSObject retainCount]
3. Retainable Object Pointers
4. Object Pointers id Class NSObject __attribute__((NSObject))
5. __attribute__((NSObject))
6. dispatch_queue_t
7. @property (nonatomic, strong) dispatch_queue_t queue;
8. Ownership Qualification
9. __unsafe_unretained
10. __strong
11. __autoreleasing
12. __weak
13. id objc_storeWeak(id *object, id value)
14. objc_clear_deallocating
15. objc_arc_weak_unavailable
16. Property Declarations assign __unsafe_unretained copy -copy + __strong retain __strong unsafe_unretained __unsafe_unretained weak __weak
17. Blocks
18. `strong` vs `copy`
19. Always use copy
20. @property (nonatomic, copy)
21. dispatch_block_t block = ^{ NSLog(@"Hello World!"); }; ! NSArray *blocks = [[NSArray alloc] initWithObject:[block copy]];
22. Retain Cycle
23. - (void)startOperation { NSOperation *operation = [[NSOperation alloc] init]; ! [operation setCompletionBlock:^{ NSLog(@"Completion for %@", operation); }]; }
24. Operation Completion Handler
25. - (void)startOperation { NSOperation *operation = [[NSOperation alloc] init]; __weak NSOperation *weakOperation = operation; ! [operation setCompletionBlock:^{ NSLog(@"Completion for %@", weakOperation); }]; }
26. The Dealloc Problem
27. Releasing UIKit objects in background threads
28. CoreFoundation is not subject to ARC
29. CFRelease(stringRef);
30. UIColor *whiteColor = [UIColor whiteColor]; CGColorRef whiteRef = [whiteColor CGColor]; ! // Crash when using whiteRef
31. UIColor *whiteColor = [UIColor whiteColor]; CGColorRef whiteRef = CGRetain([whiteColor CGColor]); ! // Use whiteRef ! CGRelease(whiteRef);
32. Exceptions
33. -fobjc-arc-exceptions
34. Fast Enumeration
35. for (const __strong NSObject *object in objects) { NSLog(@”Object: %@”, object); }
36. Faster Enumeration
37. for (const __unsafe_unretained NSObject *object in objects) { NSLog(@”Object: %@”, object); }
38. Does this actually have any real world benefits?
40. KFNumber
41. Tagged Pointer
43. Twitter: @kylefuller GitHub: kylef ! http://kylefuller.co.uk/