Fast enumeration with index in Objective-C

PINForEach.h

/**
 * Performs fast enumeration and keeps track of the enumeration index for you.
 * If you don't need the index, you can use for-in directly, or pass `_` for the index name.
 * Fast enumeration is _much_ faster than block enumeration, mostly due to the removal
 * of many calls to -retain/-release. The only case where block enumeration is justified
 * is in NSDictionary (if you need both key&value) and NSIndexSet.
 *
 * Example:
 * PINForEach(NSString *str, self.titles, row, ({
 *    NSLog(@"Title %zd: %@", row, str);
 * }));
 */
#define PINForEach(element, collection, index, body) ({                      \
   NSInteger index = -1;                                                     \
   for (element in collection) {                                             \
      index++;                                                               \
      body;                                                                  \
   }                                                                         \
})