how can I get the array index within an “for (id item in items)” objective-c loop?

Question

Alternatively, you can use -enumerateObjectsUsingBlock:, which passes both the array element and the corresponding index as arguments to the block:

[items enumerateObjectsUsingBlock:^(id item, NSUInteger idx, BOOL *stop)
{
    …
}];

Bonus: concurrent execution of the block operation on the array elements:

[items enumerateObjectsWithOptions:NSEnumerationConcurrent
    usingBlock:^(id item, NSUInteger idx, BOOL *stop)
{
    …
}];