Memory Management in iOS App Development

Transcript

1. Memory Management for iPhone Application Development Sumin Byeon (sumin@cs.arizona.edu)
2. Advanced Topic
3. Significance Limited memory (128MB, 256MB) No garbage collection No virtual memory User experience
4. Related Functions alloc copy retain release autorelease
5. Alloc Allocates memory for an object, and returns it with retain count of 1[1]. Almost equivalent to the new keyword in C+ +, Java, etc. [1] http:/ /developer.apple.com/mac/library/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmPractical.html
6. Copy Makes a copy of an object, and return retain count of 1.
7. Master Theorem #1 If you allocated it, you should release it. If you didn’t explicitly allocate it, don’t release it.
8. Example ! NSString *str = [[NSString alloc] initWithCString:"Boom baby"]; ! NSLog(str); ! [str release];
9. Example ! NSString *str = [NSString stringWithCString:"Boom baby"]; ! NSLog(str);
10. Retain Increases the retain count of an object by 1.
11. Release Decreases the retain count of an object by 1.
12. Master Theorem #2 If an object is being retained by something else, you may release it immediately. (e.g. [UIView addSubview:view])
13. Master Theorem #3 Don’t you dare call dealloc. Always call release, and dealloc will be called when the retain count becomes zero.
14. Autorelease
15. Autorelease with Threads
16. Instruments Charles Magahern (zanneth@zanneth.com)
17. Questions?