關于 NSAutoreleasePool中 release 與 drain 差別

 蘋果官方文檔的翻譯

In a garbage collected environment, release is a no-op. NSAutoreleasePool therefore provides a drain method that in a reference-counted environment behaves the same as calling release, but which in a garbage collected environment triggers garbage collection (if the memory allocated since the last collection is greater than the current threshold). Typically, therefore, you should use drain rather than release to dispose of an autorelease pool.

在一個garbage collected(垃圾收集)環境裡，release不做任何操作。 NSAutoreleasePool是以提供了一個 drain 方法，它在reference-counted(引用計數)環境中的行為和調用release一樣, 但是在一個garbage collected(垃圾收集)環境中則觸發garbage collection(垃圾收集)動作 (if the memory allocated since the last collection is greater than the current threshold)。 是以通常你應該使用drain而不是release去釋放一個autorelease pool。