NSAutoreleasePool的官方解释
Important If you use Automatic Reference Counting (ARC), you cannot use autorelease pools directly. Instead, you use @autoreleasepool blocks instead. For example, in place of:
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init; // Code benefitting from a local autorelease pool. [pool release];
you would write:
@autoreleasepool {
// Code benefitting from a local autorelease pool.
}
@autoreleasepool blocks are more efficient than using an instance of NSAutoreleasePool directly; you can also use them even if you do not use ARC.
xcode4.3引入ARC，release这块就有些变化，当你使用ARC，就必须将NSAutoreleasePool的地方换成 @autoreleasepool
http://marshal.easymorse.com/archives...
两者的作用时间不一样。AutoReleasePool对象的写法作用于运行时，@autoreleasepool作用于编译阶段。如果要启用ARC的话，在编译阶段就需要告诉编译器启用自动引用计数管理，而不能在运行时动态添加。
现在苹果推荐都使用@autoreleasepool{},无论是否使用ARC