??????δ???????α????????????autorelease????

???????????NSAutoreleasePool??ο?????????

????24. ??????????

???????????bundle?м???????????????????????`imageNamed`????????`imageWithContentsOfFile`???????????????

???????????????????????????????????????????????????????

????`imageNamed`?????????????????????`imageNamed`???????????:

??????????????????????????????????в????????????????????????????????????????????????????????????????????????м???????沢???????????

?????????`imageWithContentsOfFile`??????????

?????????????????????????????÷?:
 
UIImage *img = [UIImage imageNamed:@"myImage"]; // caching
 // or
 UIImage *img = [UIImage imageWithContentsOfFile:@"myImage"]; // no caching

???????????????????????

????????????????????????????????????????????????????????`imageWithContentsOfFile`?????????????????????????????

???????????????????????????`imageNamed`?????????????

????25. ?????????????

????????????`NSDateFormatter`???????????????????С??????????????????κ????????`NSDateFormatters`???????????????

?????????????????????????????????C?????????????Sam Soffes??????????????(http://soff.es/how-to-drastically-improve-your-app-with-an-afternoon-and-instruments)???????Щ????????????ISO-8601??????????????????д???????????????

????????????C???????????????????????????????????и???????!

???????????????????????????????????????Unix?????????????????????????NSDate:
 
- (NSDate*)dateFromUnixTimestamp:(NSTimeInterval)timestamp {
 return [NSDate dateWithTimeIntervalSince1970:timestamp];
 }

?????????????C???????????????????!

?????????????????web API????????????????????????????????javascript?и???????á??????`dateFromUnixTimestamp`??????1000?????

???????????

??????????ЩWWDC?????????????????app???????????????????????????????Apple ID??????????????????????????WWDC 2012???????

????#406: Adopting Automatic Reference Counting

????#238: iOS App Performance: Graphics and Animations

????#242: iOS App Performance: Memory

????#235: iOS App Performance: Responsiveness

????#409: Learning Instruments

????#706: Networking Best Practices

????#514: OpenGL ES Tools and Techniques

????#506: Optimizing 2D Graphics and Animation Performance

????#601: Optimizing Web Content in UIWebViews and Websites on iOS

????#225: Up and Running: Making a Great Impression with Every Launch

?????Щ01???WWDC???????м??:

????#308: Blocks and Grand Central Dispatch in Practice

????#323: Introducing Automatic Reference Counting

????#312: iOS Performance and Power Optimization with Instruments

????#105: Polishing Your App: Tips and tricks to improve the responsiveness and performance

????#121: Understanding UIKit Rendering

?????????Щ???????????????????iOS 5 Tech Talks??

????Your iOS App Performance Hitlist

????Optimizing App Performance with Instruments

????Understanding iOS View Compositing

?????????Your iOS App Performance Hitlist?????Michael Jurewitz???????Ole Begemannд?????????????????

????Apple??????????????????“Performance Tuning | ???????”???????