difference between drain, release,dealloc and retain in Objective-C/

开发者_高级运维Hi i want to know the difference between drain, release,dealloc and retain in Objective-C.

• retain increase the reference count on an object
• release decreases the reference on an object
• drain is used in place of release on ONLY for NSAutoreleasePool objects due to some arcana related to the Objective C garbage collection
• dealloc is called by the system once the retainCount of an object hits 0. It is where you clean up various things your object has (like a deconstructor or finalizer). You should NEVER call it directly, except for calling [super dealloc] at the end of your dealloc routines.

You really should just read through Apple's memory management documentation.