indexOfObjectPassingTest

[HAC]

Hello,
 On pages 364 & 365 of the third edition, it indicates that indexOfObjectPassingTest should call the block once for every element in the array unless the stop variable is set to YES. However, in debug I seen that indexOfObjectPassingTest will stop processing the array once the block returns YES, regardless whether the stop variable has been set to YES or not. In the following example method (from pages 364, 365) the intent is to return an array with all of the address cards which name matches the passed name. However, it will return an array with only one element, even if that are is more than one match.

-(NSMutableArray *) lookupAll: (NSString *) theName
{
    NSMutableArray *matches = [NSMutableArray array];
   
    NSUInteger result = [book indexOfObjectPassingTest:
                          ^ (id obj, NSUInteger idx, BOOL *stop)
                         {   
                              if ([[obj name] caseInsensitiveCompare: theName] ==
                                  NSOrderedSame) {
                                  [matches addObject: obj];
                                  return YES;
                              }
                              else
                                  return NO;
                          }];
   
    // See if we found a match
   
    if ([matches count])
        return matches;
    else
        return nil;
}

So it seems that in the case of indexOfObjectPassingTest the stop variable is intended to stop processing only in the case where no element has passed the criteria. Please correct me if I'm wrong. 

-thanks,
Hugo.

[skochan]

The indexOfObjectPassingTest: method will only return the lowest index number that passes the test, no matter how many times you call it.   It seems as though through your experimentation that you discovered that it will stop once it finds a match, which I guess seems logical.  To get all the index numbers, you need to use the indexesOfObject:   Interesting observation!

Cheers,

Steve