Manual retain with ARC

Question

Before ARC I had the following code that retains the delegate while an async operation is in progress:

- (void)startAsyncWork {     [_delegate retain];     // calls executeAsyncWork asynchronously }  - (void)executeAsyncWork {     // when finished, calls stopAsyncWork }  - (void)stopAsyncWork {     [_delegate release]; } 

What is the equivalent to this pattern with ARC?

Answer 1

I have occasionally needed to manually retain and release things (sometimes just for debugging) and came up with the following macros:

#define AntiARCRetain(...) void *retainedThing = (__bridge_retained void *)__VA_ARGS__; retainedThing = retainedThing #define AntiARCRelease(...) void *retainedThing = (__bridge void *) __VA_ARGS__; id unretainedThing = (__bridge_transfer id)retainedThing; unretainedThing = nil 

This works by using the __bridge_retained and __bridge_transfer to cast things to and from (void *) which causes things to be retained, or to create a strong reference without calling retain.

Have fun, but be careful!

Answer 2

Why not just assign your delegate object to a strong ivar for the duration of the asynchronous task?

Or have a local variable in executeAsyncWork

- (void)executeAsyncWork {     id localCopy = _delegate;      if (localCopy != nil) // since this method is async, the delegate might have gone     {         // do work on local copy     } }