Setting NSError within a block, using ARC

Question

I wish to set an NSError pointer from within a block in a project using automatic reference counting. What follows is a simplified version of my code:

- (BOO         


        

Answer 1

Note: As of 2020, this workaround is no longer necessary.

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Try this:

// ...
__block NSError *blockError = nil;
[items enumerateObjectsUsingBlock:^(id item, NSUInteger idx, BOOL *stop) {
    NSError *localError = nil;
    if (![blockSelf doSomethingWithItem:item error:&localError]) {
        blockError = localError;
    }
}];
// ...

As for exactly why this is necessary, I'm still trying to get a grasp on that myself. I'll update this answer when I do. :)