iOS Components and Frameworks: Understanding the Advanced Features of the iOS SDK

ARC Qualifiers

There are four ARC qualifiers for object ownership that tell the compiler how to handle each object. The qualifiers are specified either implicitly (__strong is the default) or explicitly when declaring an object.

__autoreleasing: autoreleasing is not the same as autorelease; rather, it is used for passing an object by reference, as in this example:

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 __autoreleasing NSError *error = nil;self.listArray = [moc executeFetchRequest:fetchReq                                    error:&error];

__strong: strong ...