What is difference between [pool release] and [pool drain]? [duplicate]

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What's the difference between sending -release or -drain to an Autorelease Pool?

I just got always wondered about difference between [pool release] and [pool drain]..

When we create a View-based application in IOS, use [pool release].

When we c开发者_StackOverflow中文版reate a command-line Tool in MAX OS X, use [pool drain].

why do use them differently?

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From the documentation:

In a garbage-collected environment, there is no need for autorelease pools. You may, however, write a framework that is designed to work in both a garbage-collected and reference-counted environment. In this case, you can use autorelease pools to hint to the collector that collection may be appropriate. In a garbage-collected environment, sending a drain message to a pool triggers garbage collection if necessary; release, however, is a no-op. In a reference-counted environment, drain has the same effect as release. Typically, therefore, you should use drain instead of release.

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No difference unless you're using Garbage Collection on OSX. Exactly the same on iOS and OSX w/o GC.

http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSAutoreleasePool_Class/Reference/Reference.html

joe